Turdus migratorius, American Robin

The robins are here!  For such a pretty and lovable bird, they have a very unflattering scientific name: Turdus migratorius.  The migratorius part isn't so bad, and robins are indeed migratory birds.  But why the name Turdus?  Scientific names are in Latin, and 'turdus' means 'thrush' in Latin, which is a bad deal for the robin.  A thrush is a type of bird that is usually small and plump and searches for food on the ground.  Bluebirds and wood thrushes are other common Middle Tennessee thrushes.

A male robin.

Robins are grayish with rusty undersides.  The males' heads are darker than their backs, and their underbellies are usually brighter than females'.  Last week a male and female were getting to know each other at our outdoor classroom. 

A female robin.

 In Nashville, this time of year robins are just finishing up their winter migration.  Robins group together near the end of winter into massive flocks (did you notice them a couple weeks ago?), then they migrate to follow food sources and warm weather.  They may not migrate straight north like most other migratory birds do - they just go wherever life is good for robins, which explains why we have some robins here year-round.  At the end of the winter migration, birds form pairs and begin to find a home range to nest in.  They may come back to the same place as last year, but they may not.

A female robin between the two Japanese quinces.

Robins are generalists in both nesting and in feeding.  They build nests in a variety of habitats, from landscaped yards to meadows to forests.  They eat a variety of insects, worms and fruits, depending on what is available to them to eat.  In the spring and summer, they tend to eat more insects, and in the fall and winter they eat more fruit and berries.  This time of year, you are likely to see the cliché of a robin with a worm dangling from its beak.  Robins can usually find their food and shelter requirements around where humans live, so they tend to be very familiar to us.

A female foraging for ground insects or worms and a male sitting on the fence.

If the male and female I saw at our outdoor classroom become a pair, they will have 2-3 broods of baby robins this spring and summer.  The female will soon start building a cup-shaped nest of three layers: twigs first then mud then grass on the inside.  She will probably lay 3 light blue oblong eggs in the nest a couple of days after it is finished.  The female sits on the nest for 12-14 days, getting up every once in a while to turn the eggs or go get food.  The male might bring her some food or might not.  The female's belly has a patch of skin with extra blood vessels that keep the eggs warm as she sits on them.  If the eggs get too cold, they will die.  When the eggs hatch, the female tosses the egg shells out of the nest and broods (sits) for another 3-4 days.  After that, the hatchlings are able to keep themselves warm enough without being sat upon constantly.

Both parents feed the hatchlings after they escape their eggshells.  For the first few days, the menu is regurgitated food the parents already ate.  And if that isn't gross enough, after that the parents bring soft-bodied insects and worms to feed the poor little birds.  The hatchlings beg and peep like mad for their food, so they must like it.  Begging is an important skill for robin hatchlings, because the most aggressive peeper with the longest neck and widest-open beak will get the most food and is most likely to survive to adulthood. 

At two weeks old, the robins usually fledge (leave the nest).  They still don't fly well or know how to find food, so the parents hop around them on the ground alerting them to danger and bringing them insects and berries.  At first, the mom feeds the fledglings, but then when they are starting to become independent, the dad will feed them, and the mom will go and build a new nest for the next brood.  The fledgeling stage is very dangerous for the birds because the young ones can't fly yet.  They might become the food that a mother hawk brings home to her hatchlings, or they might fall prey to a cat.

There are many types of birds at our outdoor classroom right now.  Next time you go, try to count the different types of birds you see.  Last time I was there, I saw 3 kinds.  Pay special attention to the robins, and see if you can figure out what they are doing when you see them (feeding? gathering nest materials? searching for a good nest site? fighting off other birds? or are they watching you?).   

Why Don't Fish Need Mittens?

Brrrr!  It's been cold the last few nights!  Air temperatures dropped into the mid 20's, which is way lower than freezing.  I bundled up in many layers to survive being outside for about an hour last evening.  I felt a little bad for the fish in our outdoor classroom - they are stuck in cold water without any hats or mittens or even hot cocoa to warm them up.

A mosquitofish alive and well after several nights of freezing temperatures.

Humans are like tropical animals in terms of their thermal comfort zone.  We are comfortable living in temperatures in the 60's to 90's on the Fahrenheit scale.  We have created many devices to keep ourselves at a comfortable temperature: clothes, buildings, heat, air conditioning, insulation and ice cubes all help us maintain comfortable body temperatures whether we are in the tropics or in the Arctic.  Animals can be classified as endotherms or ectotherms, and we are of the endotherm variety.  Endotherms use some of the energy in the food they eat to keep their bodies warm.  Even though the temperature of the air inside our buildings is usually around 72 degrees, our bodies stay at 98.6 degrees.  Mammals, birds and even some fish like tuna can keep their body temperature warm using energy from food.

Mosquitofish are happy as clams in a much broader range of temperatures than we can stand.  They can live in the very warm water of shallow sunny pools in the summer, and they can survive a fairly cold winter too.  Mosquitofish are ectotherms, like most fish, amphibians, reptiles, insects and mollusks.  They don't keep their body temperature warm - they let it cool off when the environment cools off.  And as the temperature drops, they simply slow down.  Their bodies move more slowly, they eat less food, and they stay more hidden.  Many ectotherms hibernate, essentially sleeping in a cold state until the weather becomes warm enough to move around again.  If you watch our mosquitofish, you will notice that they are much slower on cold days than warm days. 

Mosquitofish can't survive if the pond freezes all they way through.  Fortunately for them, water temperature usually doesn't get as low as air temperature, so the pond is going to be warmer than the air temperature, and it won't usually freeze.  Also, ponds freeze at their surface, then the ice acts as an insulator, keeping the lower layer of the pond from freezing.  So even if you see ice on our pond this winter, it is likely that the mosquitofish will be swimming slowly in the water under the surface. 

Do mosquitofish feel cold?  I don't know.  I suppose you would have to put a mosquitofish in a fish tank with a cold area and a warm area and see where it chooses to spend its time!

Here are some other ways you can see organisms responding to the temperature at the outdoor classroom this week:

It's easy to see which plants survive freezing right now.  I'll write about this more in the deep winter, but it's probably easier to see now before the dead plants blow away and decompose.  The dead leaves in the picture below didn't survive freezing.  Either their seeds will survive the winter or their roots will survive in the ground, but it will not grow again until the spring.  The plant on the left is just fine with freezing temperatures, and it will stay growing, though very slowly, through the winter.  there are lots of winter-growing plants in our classroom.

The fern on the left survived freezing, the plant on the right did not.

The honey bees are still drinking at our pond on warm days!  They must have a fairly warm location for their hive.  Bees do some temperature regulation of their hives by eating food then shaking their wings really hard inside the hive to generate heat.  Our bodies do a similar thing - they shiver to generate heat.  Bees also flap their wings to fan the hive if it gets too hot.  Even though insects are ectotherms, bees have some endotherm ability.  Neat!

Honey bees are still drinking from our pond on warmer days despite the freezing nights.

A Visit From the Psyllid Fairy

What happens when you lose a tooth?  You get a visit from the tooth fairy.  What happens when you write a blog post about hackberry leaf gall psyllids?  You get a visit from the psyllid fairy!!!

Envelope of psyllids and leaf galls - what a great surprise!

A parent of a lower school student, and an accomplished naturalist, learned about hackberry leaf gall psyllids after bajillions of them emerged from the leaf galls of the hackberries around her house.  She had saved some psyllids to identify them and brought some to my mailbox in an envelope after she saw last week's post.  Here's what was in the envelope:

Two hackberry leaves with galls and five hackberry leaf gall psyllids.

Those tiny dots in the picture above are hackberry leaf gall psyllids.  The large brown things are hackberry leaves.  I decided to have a microscope photoshoot with the psyllids, so I used a camera with a narrow lens and held it up to the eyepiece of a microscope to take the following picture:

Adult hackberry leaf gall psyllid at 20x magnification.

The psyllid in the picture above is long dead and a bit dried out, but it still looks pretty good for a dead bug.  Psyllids are true bugs, and true bugs are insects in the group called Hemiptera.  Hemipterans have mouthparts that are good for sucking plant sap, which is what psyllids are up to when they are living inside leaf galls.  You can see the mouthpart of the psyilld pointing down from the head, which is on the left side of the insect.  You can also see one of its antennae pointing to the left of the head. 

Two dried hackberry leaves, each with a leaf gall.

This time of year, the above leaves are all the evidence you'll see of hackberry psyllids.  The adult bugs have hidden away in bark or in cracks around the outside of your house.

Many thanks to the psyllid fairy for the fabulous psyllids!

Help! I've Got Hackberry Leaf Galls!

Last week students in our outdoor classroom sent the picture below, wondering what it was.  It's a very logical question, since those...things are growing out of what is obviously a leaf, but no normal leaf has weird miniature mushroom-shapes growing out of it.

Hackberry Leaf Galls (photo: M. Sherman)

The leaf above comes from a hackberry tree, whose bark I think is fantastic, and which we will explore later in the winter.  We have a gigantic hackberry tree in the outdoor classroom, and it's at the end of the row of parking spaces near the road.  Here's our hackberry:

Hackberry tree with most leaves already gone for the winter.

If you search through the fallen leaves around the classroom, you can find lots of hackberry leaves right now.  They have toothed edges (lots of tiny points), and they narrow to a tip.  Also, the wider end of the leaf usually is lopsided with one side larger than the other.  Most of the hackberry leaves have one or more of those big lumps on the lower side of the leaf.  The lumps are called leaf galls, and they are scar tissue the tree has grown in self defense against a parasite.

Three hackberry leaves, two with galls, one without.

So, what exactly is a parasite, you ask?  A parasite is a small organism that lives on a larger organism and often uses the larger organism for food, harming the larger organism in the process.  The larger organism is called the host.  There are lots interesting types of parasites in this world.  Dogs and cats sometimes have fleas for parasites.  Deer often have ticks.  Humans can sometimes have lice.  And plants can have parasites too.  The parasite on our hackberry leaves can only live on hackberries, not humans.  It is a type of insect called a psyllid (SIL'-id).  Psyllids look just like tiny cicadas - smaller than a grain of rice.

I broke open this gall, but it was empty.  The adult has already emerged from it.

Hackberry leaf psyllids lay their eggs on the underside of hackberry leaves in the spring.  The eggs grow into immature psyllids that look like this.  The psyllids damage the leaves, which causes the leaves to grow a lump of scar tissue (a gall).  The psyllids eat hackberry sap and live inside the gall as they grow larger through the summer.  In the fall, the psyllids grow into adults and drill out of the gall.  They fly or crawl to find crevices in bark or buildings to overwinter safely.  When the weather warms up in the spring, they lay eggs and start the cycle again. 

Hackberries grow well in Middle Tennessee, yet they almost always have hackberry leaf galls damaging their leaves.  The trees don't seem overly harmed by the gall psyllids' damage.  This is normal parasite behavior.  Most parasites don't cause extensive harm to their hosts.  They take just a little food from them but not enough to kill them.  If a parasite ate too much of its host and killed it, the parasite would be out of food and would die too.  Parasites use their hosts in a sustainable manner so that their food source will be available in the future.

Busy Fall Ants

Edward O. Wilson is one of my scientist heroes, and he has studied ants for most of the 83 years of his life.  As a child, he loved to go outside and observe ants for hours because they exhibit such a variety of behaviors.  E. O. Wilson eventually became the world's leading myrmecologist (ant expert), as well as an expert on ecology, animal behavior and conservation biology.  Thanks to him, I know some really amazing things about ant behavior, and I always think of him when I observe ants.

A foraging ant.

The ants at our outdoor classroom are busy, busy, busy this time of year.  Frost is coming soon, and the ants are foraging for their last bits of food to help get them through the cold weather coming our way.  If you stop and observe the rocks around the pond, you will start to see some patterns in the ants' behaviors as the ants bustle around in a mad rush to get ready for winter.  Below are some patterns in ant behavior that I observed.

An ant and her shadow.

The ant above was exploring to find food, also known as foraging.  Any ant exploring on its own in a zig-zag or random fashion is most likely foraging for food.  When the ant finds food, it will pick up the food and bring its food back to the ant's nest to share with the other ants in its colony.  If there is more food than it can carry, the ant will do something incredible.  It will leave a scent trail on its return to the nest to signal to its nest mates to go and get the rest of the food!  How amazing that these tiny creatures can communicate such complex information to each other.

Ants following a scent trail.

Ants are social insects that live in colonies.  The ants in a row in the picture above are interacting as a social group by following a common scent trail.  Either they are all going to get food or they are moving their colony.  Ants usually maintain a nest in a space in or near the ground.  The nest stores their food and eggs.  The ants in the picture above are all sisters!  I know this because all worker ants are female and are sisters.  The sisters work together to keep the colony alive and take care of their mom, the queen.  The queen stays in the ants nest and lays eggs.  If you look closely at a line of ants, you might be able to see if they are carrying bits of food or eggs.  If they are carrying ant eggs, they are moving the colony.  There is a colony of ants outside my back door that moves its nest every time it rains: from under the flower pot in dry weather to under a loose brick when it's rainy.  They never seem to get tired of carrying eggs around.

Ants deciding if they are friends or enemies.

If you observe a line of ants, you will probably notice ants are going in both directions, like in the picture above.  That means the ants run into each other.  Every time an ant runs into another ant, it needs to determine if the other ant is a friend or an enemy.  Enemy ants must be run off the territory or killed and eaten, and friendly ants must be allowed to pass.  Ants don't recognize each others' faces; rather, they smell each other with their antennae.  It takes just a flash for the ants to touch antennae, recognize each other, then head on their way. 

Ants are extremely important creatures on Earth.  They live in the soil and on trees and other plants, and they help recycle nutrients in ecosystems.  Ants build soil, eat pest organisms, and provide food for other insects and for birds.  Some plants are pollinated by ants, and some seeds are dispersed by them too.  E. O. Wilson has estimated that ants account for about the same amount of mass on Earth as humans do! I wonder which has had a greater impact on our planet.  I know humans have built cities and houses and reshaped the ecosystems, but ants have built the soil that all other terrestrial ecosystems are built on.

Tube Flowers and Their Pollinators

Butterfly bushes (Buddleja sp.) are very well-named.  The ones in our outdoor classroom are usually surrounded by several butterflies flying from flower to flower and filling their butterfly bellies with nectar.  If you look closer, you'll notice that lots of types insects like butterfly bush nectar, and even hummingbirds have been known to drink from these flowers.  Because of the shape of butterfly bush flowers, not all nectar-feeders are able to use these plants.  All butterfly-bush-feeders must have long, thin mouthparts that fit into the flowers.  Notice the long curved proboscis on the skipper in the photo below.  The proboscis works like a silly straw, curving and extending into the base of each flower for a sip of nectar.

A skipper sipping nectar on a butterfly bush.

Below you can see one individual flower of the butterfly bush.  The green bit is the base of the flower where nectar is produced.  The purple petals form a tube that opens at the top of the flower.  The tube shape does a good job of keeping out insects that steal nectar without pollinating the flower.  Insects that can reach their mouthparts into the flower receive a dusting of pollen as they sip nectar.  When the insects move to the next flower, they drop off the pollen, allowing the flower to produce seeds.  Nectar-sippers and flowers have a trade-off where each organism benefits from the arrangement: flowers are pollinated and the pollinators get food.  This relationship is called a mutualism, and it is a type of symbiosis where two organisms benefit from the interaction.

A single tube-shaped flower of the butterfly bush.

The purple tube-shaped flowers have orange centers to help insects find their way into parts of the flower where the nectar is produced.  Most flowers have nectar guides in their centers.  Usually nectar guides are yellow or orange regions with lines pointing to the center of the flower.  Next time you are at the outdoor classroom, look for nectar guides in butterfly bush flowers and any other flowers you'll see.

Yellow/orange nectar guide inside a butterfly bush flower.

Below you can see two more organisms that are mutualists with butterfly bushes: bees and longhorn beetles.  Both pollinate the flowers and get fed in the process.  There are some insects that 'cheat' the butterfly bushes out of their pollen.  Some types of caterpillars, beetles and ants chew through the base of the flower, drink the nectar, and leave without pollinating the flower.  Look carefully at our butterfly bush flowers for some crime-scene evidence:  if you see holes chewed through the base of their tubes, you know the nectar has been stolen with no pollination payment in return!

Bumblebee and longhorn beetle working the butterfly bush flowers.

Interesting side not:  The bumblebee in the photo above was not actively feeding.  It was just holding on and resting.  This time of year, the temperatures are dropping, and insects that don't overwinter are nearing the end of their lifespan.  It could be that this bee is slowing down because it is old.  Alternately, the bee could be finding its home for the night, since I took this photo in the early evening.  Bumblebees often sleep in large flowers or near small flowers so they have a food source in the morning (wouldn't you love to sleep in a flower?).  A third possibility is that the bee is just slow because the temperature is lower.  Some bees just slow down when the temperature drops, stay in a torpor through the cold winter, and then speed back up again in the summer when it's warm.

Invasion of the Blue Dasher Dragonflies

Blue dasher dragonfly.  Are those aviator sunglasses?

The outdoor classroom and back field of our school has been a-buzz with these miniature blue helicopter-like insects.  They are a type of dragonfly called blue dashers (scientific name Pachydiplax longipennis, which means double-thick long wings, by the way), and they are beautiful!  The one above is an adult male, which you can tell from the bluish color of his abdomen.  Females and young adult males have brownish-black abdomens.  Both males and females have brown and yellow wavy stripes on their mid-section, or thorax.  Blue dashers all have a white head with bluish-green eyes.  In the picture above, the white patch on the head is the upper and lower mandible, which the dragonfly uses to bite its prey.

Dragonfly eyes are amazing.  They cover most of the head and provide the dragonfly with a 360 degree view of their world.  Dragonflies need excellent vision of their surroundings because they can fly and maneuver so quickly.  If they couldn't see in all directions, they'd constantly be smashing into things.  Dragonflies fly quickly because they need to catch their prey, which consists of insects that can also fly.  Blue dashers specialize in mosquitoes, gnats and flies, but they also eat butterflies and grasshoppers.  

Blue dasher demonstrating its helicopter shape, with a long abdomen to balance the head.

Since dragonflies are so big and fast, sometimes people are afraid of them.  The good news is that dragonflies are harmless to humans.  They do not bite or attack humans, and the long, pointy abdomen does not sting.  The shape of the abdomen serves as a counter-weight to the head, keeping the body of the insect level as it is suspended by its wings in flight.  If you look at the picture above, you can see how the head and tail appear to balance each other out under the wings.  Blue dashers are particularly useful on the school grounds because they keep other biting insects away from the kids' outdoor areas.

All dragonflies lay their eggs in water, and we probably have blue dasher nymphs in our pond at school.  After being deposited in the water, dragonfly eggs hatch into nymphs (underwater larvae), which grow and eat other aquatic insects and tiny fish until they are big enough to metamorphose into adults.  When a dragonfly becomes an adult, it crawls out of the water onto a stem or rock, splits its exoskeleton, and drags itself out of the shed skin as a fully-formed adult.  Blue dasher nymphs are particularly tolerant of poor water conditions, which makes them ideal for living in an urban environment.  They are widespread around the United States and in southern Canada in all variety of habitats. 

Dragonfly nymph exoskeleton. (Photo: Mary Entrekin Agee)

What's with all the grass spiders?

Note: If you've tried to sign up to receive my posts by email, I think I've fixed the problem.

It's the strangest summer.  Everything has looked like August since the middle of June.  The leaves are starting to yellow and fall, the current weeds are ones you see in August and September, and the yellow jackets are out, even though I usually only see those in September.
 
One thing that really stands out is all the grass spiders' funnel-shaped webs that seem to have popped up everywhere.  They seem to blanket the hillsides at Radnor Lake, but they are also all over the place in the less-traveled parts of our yard.  They look like sheets of spider web with a funnel in one corner.

Grass spider web.

Since I only remember seeing them in late August and September, I assumed that was their active season.  It turns out that they are active all summer, but the dry dust gets caught in their webs, making them visible.  We are seeing them now because we've only had a quarter inch of rain since the end of May, and everything is really dusty.  Grass spiders are not taking over the world - they've been here all along.

White patches are grass spider webs.

Grass spiders are neat spiders.  They build their sheet web with a little hidey-spout to sit in.  They often dangle some web threads over the sheet too.  Any insect that stumbles onto the sheet or flies into the threads and drops is doomed.  The web isn't sticky, so the insects aren't trapped; rather the web spider is shockingly fast and races out from the funnel as soon as it feels a victim on the sheet.  You can observe this phenomenon yourself if you catch an insect and drop it on a grass spider web. Grass spiders kill their prey with venom, like most spiders do.  They don't bite people, and the venom is harmless to us if they are forced to bite you (if you pick one). 

Grass spider web with funnel in the middle.

Grass spiders are beneficial organisms.  They eat pest insects and help me with pest control in the vegetable garden.  I'm glad to have them in the yard.  They tend to stay put on their webs, so I don't find them in our house very often.  Male grass spiders do go a-wanderin' when it's time to find a mate.  They must have a defined mating season, because it seems one night every spring I walk into my kitchen (near the back door that isn't sealed very tightly), turn on the light, and there are two or three male grass spiders searching for love on the kitchen floor.  Here's a link to see what grass spiders look like (they are only about an inch across, but the picture makes them look gigantic). 

Growing Black Chickpeas

I met a fascinating plant on the farm this week - the black chickpea.  I'm accustomed to seeing tan chickpeas in the grocery store, but it turns out that chickpea skins come in the same variety of colors as human skins - light tan through yellow to red, dark brown and black.  Maybe it's because I am reading the Hunger Games trilogy (probably shouldn't have admitted that), but these plants sound like something that would be found in the arena - useful and dangerous at the same time.  You'll have to see if you agree with me - check it out:

Chickpea (Cicer arietinum) flower.

Chickpeas (Cicer arietinum) have miniature pea flowers, with the typical pea's asymmetrical petals.  The flowers each contain a tiny, elongate ovary that will elongate into a pod with seeds once the flower is pollinated.  Each pod contains one to three seeds, many fewer than English peas.  Chickpeas, regular peas and beans are all in the same plant family - the fabulous Fabaceae, or legume family.

Green chickpea pods.

The leaves and youngest green pods of chickpeas can be eaten raw.  The enlarged but green pods can be cooked like regular peas.  The mature pods turn brown and contain dry seeds. These seeds are usually eaten cooked.  The black chick peas do not turn black until they are mature and dry, and they retain their black color even after they are cooked.  Regardless of skin color, all chick peas are the same on the inside - tan. 

Chickpea pods and leaves with acid secretion making the plant glisten.

The really strange thing about chickpeas is that their leaves and pods secrete a liquid that contains a dangerous soup of acids (Katniss would know that!).  When you brush against these plants, they feel moist.  If you have any scratches on your skin, you will notice that the secretion burns painfully.  If you go blackberry picking one day then chickpea harvesting the next, you will be uncomfortable!  I imagine if you picked them all day, you might have some skin erosion.  On large farms, chick peas are harvested by machine, so don't worry too much about fingerless chickpea harvesters.  The acid is very useful to the plant.  If you were a disease organism or an insect looking to eat a garbanzo bean plant, you would definitely change your mind when you were burned by the malic, oxalic and hydrochloric acids on the plant.

Besides deterring pests, the garbanzo bean secretion does another important job.  It works just like sweat and keeps the plant cool!  The plants secrete their sweat later in their lifespan when their seeds are mature, and presumably when the growing season is edging toward summer heat.  The sweat keeps their leaves and pods cooler than non-sweating leaves when the temperature is high.  As what happens when we sweat, the plants lose water.  They are at risk of dehydrating if there is not enough soil moisture for them to absorb.  Also, moist things tend to rot or become infected as a general rule, so the acid is necessary to protect the moist plants from rotting.

Nearly dry chickpea pod.

The acid secretion on chickpea plants is both useful and harmful to people.  It tastes good, since acids taste sour.  In fact, one of chickpea's acids is malic acid, which provides the tartness in apples.  The acid secretion can be collected by draping a thin cloth over the leaves, letting it sit all night until dew forms, then wringing out the cloth.  It can be used to make a unique lemonade-type drink.  The harmful part comes from oxalic acid.  Oxalic acid interferes with the absorption of calcium and some other minerals from food, and it can aggravate kidney stones.  Oxalic acid is also found in spinach, and that's why spinach and chickpea leaves should not be eaten every single day, though moderate consumption is harmless.. 

Black Kabuli chickpea.

Above is a black garbanzo bean (chickpea) freshly picked.

So what's the verdict?  Would chickpeas make a great Hunger Games plant?  Edible but covered in burning acid - perfect!

Trilobites at the Chicago Field Museum

Museums can make great places for social outings, but I also love going to them alone.  I can skip the uninteresting parts and obsess as much as I want over the good parts.  On a recent trip with friends to the Field Museum a few weeks ago, the miles of enticing, juicy exhibits drove me mad with unsatisfied curiosity.  So I went back by myself and spent an entire day!

Who knew trilobites had such amazing appendages?

There was so much to see, but my absolute favorite was their collection of exquisitely articulated trilobite fossils.  Trilobites were among the earliest Arthropods, which are the jointed-appendaged animals like insects, spiders and roly-poly bugs.  They were commonly-fossilized animals from about 525 million years ago through 250 million years ago, which is an astonishingly long period of time in evolutionary history.

Trilobites are so much cuter with antennae.

I'm not sure how these fossils were separated from their surrounding rock, but their details are incredible.  Looking at these fossils, I could imagine these little critters skittering across the ocean floor and using those appendages to sense water movement and scent of prey items.

Trilobite diversity.

The exoskeleton of trilobites was thick and tough, which made it easier for fossils to form.  Scientists have been able to study the evolution of eye structures, other sense organs and delicate feeding apparatuses over time using trilobites.  There was considerable diversity of trilobite species.  It is not understood why trilobites went extinct.  Their closest living species relative alive today is probably the horseshoe crab.

A trilobite called Walliserops with what has to be a smell/taste organ on its front end.

Maples in Early Spring

If you live in the temperate eastern United States, and you only know one kind of tree, it's probably going to be a maple.  Everyone knows maples.  People either recognize and love maples' unique, pointy leaves, enjoy maple syrup, admire bright fall maple trees, or played with maple helicopter seeds as kids.  Few people know what maples are up to this time of year, though.

Even without leaves, maples are very busy this time of year.  Look at the ends of the branches on this maple tree below:  there are lumps all along the branches.

Swollen maple buds ready to pop.  Early March.

Those lumps are flower buds.  Many maples flower and fruit before they leaf out.  Here is a closeup of maple flowers:

Mid March, maple flowers.

Maple flowers are pollination generalists.  Some are pollinated by insects and bees, some are wind pollinated, and some are self-pollinated.  From the tree's perspective, it pays to be flexible with pollination strategies if you bloom very early in the growing season, because it's difficult to insure that insects will be out when you're ready to bloom.  Insects are really the best pollinators.  They are great at pollinating over long distances with small amounts of pollen, but they require warmer temperatures to do their work.  Wind pollinates cheaply - you don't have to feed it nectar or a portion of your pollen to get it to carry your pollen to another flower.  But wind isn't very specific in direction, so you usually need to make a lot of pollen if you are using wind (more on this next time!).  Self pollinating is convenient, but let's face it, you don't get much genetic variety if you make kids using only your own genes. 

Either way, lots of pollination has happened, because the maples in Chicago are LOADED with maple fruit.  Notice I called these helicopter things seeds earlier in the post, and now I'm calling them fruit.  I didn't want to alarm you earlier, but here's how this works:  fruits are plant parts that hold seeds.  An apple fruit has seeds in it, and so does a cucumber, and so does a maple fruit.  The maple fruit consists of a wing and a case around the actual seed.  Open up the swollen end of the fruit, and you will find a sticky seed (and you can stick the fruit on your nose or fingers like we did when we were kids).

Maple fruits (samaras) in late March.

Maple fruits are winged, and they are adapted to being carried far away from their parent tree by the wind.  They do indeed work like helicopters - their wing catches the wind and spins them along to hopefully sunnier ground than the ground just under their parent tree (maples are indeed shade trees).  There are many types of fruits out there: berries, capsules, hesperidia, drupes, pepoes, etc.  Fruits with wings are called samaras.  Both maples and ash trees have samaras to carry their seeds away.

New (red!) maple leaves, plus some maple samaras, late March.

Above you can see some new leaves just starting to grow on this maple. I had to look hard to find maple leaves on this type of maple tree - they mostly have only fruit right now.  Below you can see two pictures of early leaf growth on a Japanese maple.  Japanese maples seem to usually leaf out before they set fruit.

Japanese maple leaf buds opened and showing the new expanding leaves, late March.

Slightly older Japanese maple leaves, late March.

Green Lacewing: Teenage Hellion

The common green lacewing, Chrysoperla sp., is a welcome insect in my garden and on the farm, but it sometimes reminds me of Dr. Jeckyll and Mr. Hyde.  It has rather alarming personality shifts.   It starts and ends life with delicate, gentle beauty, but it has a dramatic personality change during its ferocious adolescent stage.  

Green Lacewing Eggs

The miniscule space needles growing out of the shefflera stem above are not fungi.  They are the slim, stalked eggs of the green lacewing.  Lacewing eggs are usually laid on the undersides of leaves and stems.  They are a lovely surprise to find when working in the garden.  They seem so fragile that they would break or bend in the breeze, but you can brush your finger against them and they stand back up.  They are so delicate, that I can't feel them, even with my less calloused ring fingers.  They stand in peaceful beauty, glistening in the sun, while their infant lacewings develop inside each egg.  

Watch out, because after a few days, each egg cracks, and out charges a fierce, anxious monster of a teenage insect: the green lacewing larva.  It moves quickly and ranges widely, and it is hungry for fresh meat. It stalks, catches and eats every insect it can catch with its pointy mouth parts.  It kills its prey with toxic venom.  If it were 100 times larger, you would have to fortify your house and never go outside!  I'm certain some dangerous movie aliens are based on these ravenous killers. 

Scary green lacewing larva, source in picture.

After a few weeks, the green lacewing larva begins to feel full.  Its hunger for protein is sated.  It's ready to settle down, take up a peaceful existence and devote itself to future generations.  It finds a sheltered space under a leaf, wraps itself into a silk-bound ball, and metamorphoses into an adult.  The adult emerges, green and shimmering, and spreads its delicate, reticulated wings.  It floats off into the night, sipping nectar, mating and laying eggs.

Green lacewing adult with outstretched right forewing.

Don't fear the lacewing, even in its carnivorous stage.  It won't bite or sting you.  It will, however, remove hundreds of pest insects from your garden.  One lacewing larva can eat 200 aphids in a week!  Some organic gardeners buy and release lacewings onto their farms to help control insects.  Pesticides kill these useful farm workers, allowing pest insects to move back into the area with no predators.  Since pests can usually reproduce faster than prey, if both pests and prey are killed, you're likely to have a worse pest problem in a few weeks when the population recovers.  Encouraging beneficial insects like the green lacewing helps cut down on expenses, work and pesticide usage.  To encourage lacewings, plant flowers that the adults like, for example coreopsis, dill, Queen Anne's lace, cosmos and other similar plans.  You can also leave some of your dandelion weeds, because lacewings love them.

I apologize to my biologist readers for all the anthropomorphizing above, but these little critters seem very dramatic to me. 

Little Green Farm Workers

With the greens of the farm plants fading, two bright green animals brought themselves to our attention on the farm this week.  Both of them are welcome creatures that help us keep the numbers of pest insects low. 

The first green creature of the week, a rough green snake, was hanging out in the barn.  I found him in a basket I was about to use for eggplants.  We quickly caught him and put him in this jar (with air holes), so that the farm owner's son could see him too.  These little green snakes are a rare sight on the farm, and they hold a special place in the hearts of this farm family.  We marveled and the bright emerald luminescent color of this sleek, friendly snake.

Rough Green Snake with grass- we released him quickly!

Rough green snakes don't get large.  They can grow to almost 3 feet long, but they always stay skinny.  They are great climbers and spend their time hunting insects and spiders in any kind of vegetation from grass to trees, but they prefer to be higher up rather than on the ground.  Green snakes are well camouflaged for their preferred habitat, and I've probably seen dozens of them without realizing it.  They coil up in branches to sleep at night, and in the cooler weather, they seek refuge under logs or other debris.  This may be why our green snake ventured into the barn.  He probably thought he found a good place to overwinter.

Later in the week, we were working in the greenhouse, and we found two gigantic praying mantises, both the brightest of green.  One of the mantises was half brown and the other was all green.  I wrote a little about mantids earlier, but here's some more information about them.

In Tennessee, our most noticeable mantids come in three color variations: green, brown, and green plus brown.  The green ones are European mantids, the brown are Carolina mantids, and the green plus brown are Chinese mantids.  Only the Carolina ones are native, and the other two were introduced to the US to help control garden pests.  These introduced species do not appear to be particularly invasive, though they can reduce numbers of helpful organisms like wolf spiders.  People generally regard them as welcome workers in farms and gardens.   There are several other mantis species that are illegal to import because they pose a threat to native ecosystems.  They can probably reproduce very quickly and overeat beneficial insects.

European mantis, about 6" long.

Female mantises are disconcertingly large this time of year.  They grow big from hunting all season, and their abdomens are filled with eggs.  Now they are laying their egg cases on vegetation.  The egg cases look like brown trilobytes - they are oblong with ridges and about 1-2" long.  They are eggs encased in a foamy mass that hardens after it is laid.  The eggs overwinter to hatch in the spring, releasing hundreds of tiny, springy green mantises into the area.  The tiny, thin mantises need to disperse fast, because their siblings pose a significant predation threat.

Dangerous Animals Week, Part II

Black Widow Spider (Source)

I bet that image caught your eye!  There is no mistaking a female black widow spider.  When you see one, it is startling.  They are so black and shiny, they stand out against any background.  In my opinion, the extreme blackness of black widows is their most charismatic characteristic - even more so than their red markings.  They are the same black as Wonder Woman's hair.  Their red markings are more variable than you learned in third grade.  Yes, they commonly have a red hourglass under their abdomens, but by the time you notice the red abdomen, you've gotten really close and you've turned over the spider, and it's too late!  Several species of black widow have red splotches on the dorsal side of their abdomens, but the southern black widow has no dorsal splotches.  If you see a jet black shiny and fairly large spider, don't pick it up!

I saw two black widow spiders this week on the farm.  That makes five so far this summer.  I've come to expect them in the drier areas of the farm, like inside the hoop house and the barn.  They also seem more likely to be present on human-made structures, like the irrigation equipment, though this week's spiders were low to the ground on plant stems.  Can you see the black widow in the picture below?

Yes, there is a black widow here.

Here I have zoomed in on the unlucky black widow:

There it is!

When you encounter a black widow, you will notice a rather strange spider web.  Black widows weave chaotic, disorganized and somewhat sparse webs.  Their silk seems to be stronger than other spiders if you happen to put a finger through a web.  The silk has been tested, and it's not stronger, but it is very sticky and somewhat thicker than what other spiders extrude.

For a person who, as a child, thought black widows were always on the hunt for an unsuspecting human to bite, real-life black widows seem shockingly meek.  They cower if their webs are disturbed.  They don't jump or run, but they hold still and hope their warning coloration convinces you to just go away.  The spider above seemed to crouch with it's little legs over its head and quiver when I uncovered it.  I was sorry to kill it, but their bites are so dangerous, we can't tolerate them on the farm.

When you look up black widow spider bites, the medical sites reassure you that 'black widow spider bites are rarely lethal'.  Thanks - that makes me feel a lot better!  Actually, I, personally, am not at great risk, but a bite to a child, elderly person or ill person can be fatal.  Black widows produce a very potent neurotoxin that can spread through the body.  It can produce systemic symptoms like fever, sharp pains, nausea, tremors and worse.  The actual bite location itself will be relatively unimpressive, with a small, red, swollen area.

Most black widow bites are not treated with antivenom (aka antivenin, if you're using the French-derived version of the word).  The antivenom is problematic because it is rarely stocked at hospitals, and it's made from horse serum, which can cause major allergic reactions.  If you are bitten by a black widow, treated with antivenom, then bitten by a rattlesnake, you will be in big trouble.  Rattlesnake antivenom is also made with horse serum, and after your first exposure, your immune system will react much more strongly to the second exposure of horse serum.  Use of antivenom can save the life of an at-risk individual, and it can shorten the flu-like symptoms of a healthy person. 

Black widow spiders get their names from one of the behaviors observed in the female black widows.  Sometimes after mating, female black widow spiders eat the male black widow.  Male black widows generally get the short end of the stick in life.  They are very small, their coloration is drab and they don't have enough venom in their bites to bother anyone.  Their main job in life is to mate and pass on their genes, and after that, they may as well provide a little food to the mother of their children.

Now that the days and nights are getting cooler, I've noticed that the cold-blooded animals on the farm have slowed way down.  The chiggers and ticks seem less intent on making life annoying.  The bees and wasps have mostly disappeared.  The black widows have finished laying eggs and have hopefully lost the strength to push their fangs in through the calloused skin on my hands.