Outside My Window

Earlier this month Tim Vechter found this Polyphemus moth on a tree trunk in the city’s Shadyside neighborhood. 

Finding such a huge moth — with a wingspan of 6″ — is always amazing but even more so in the city where we don’t expect to see wildlife.

It probably likes Shadyside’s habitat.  Polyphemus don’t eat when they’re moths but as caterpillars they feed on a wide variety of deciduous trees including oak, maple, hickory and beech.  Shadyside’s tree-lined streets provide a nice selection of mature host plants.

When Pittsburgh was a smoky city the moths probably weren’t here but all it took was one female to make the leap back to town.  The males’ bushy antennae can detect female pheromones from miles away and they’ll fly that far to mate with them.

Polyphemus moths are noticeable because of their huge size and the purplish eyespots on their hind wings.  Those two traits gave them their name. 

Polyphemus was the one-eyed giant who ate six of Odysseus’ men.  He was well known among the Cyclops.  His name means “famous.” 

(photo by Tim Vechter)

If you haven’t seen these webs in the trees, you will soon.

These are the communal webs of fall webworm caterpillars (Hyphantria cunea).

Their mother laid a mass of eggs on a deciduous tree, preferably a cherry, apple, ash or willow.  A week later the eggs hatched into tiny caterpillars and they began to build their web, mostly at night. 

The caterpillars live inside the web, molting as they grow, and extending it to surround the leaves they’re eating.  The web can become as much as three feet long but it’s very different from the tent webs we see in the spring. 

Tent caterpillars build in the forks of branches and come out of their nest to eat.  Fall webworms build at the tips of branches and stay inside to eat, only emerging on very hot days (too hot to stay inside!) or when they’ve reached their final instar and are ready to pupate.

Hyphantria cunea overwinter in the pupal stage under loose bark or debris on the ground.  When they emerge in the spring they look like this with a 2″ wingspan:

Unless you have an infested orchard, fall webworms aren’t that bad for trees and they’re quite good for birds. 

The caterpillars don’t permanently harm the trees because they’re eating the leaves at the end of the growing season when the trees would drop them anyway. 

And they’re an important food source for birds.  Migrating warblers see the webs as huge advertisements:  “Come eat!  Good protein inside!”

When you see fall webworms in the trees, think “happy warblers.”

(Web photo by G. Keith Douce, University of Georgia, Bugwood.org.  Moth photo from Wikimedia Commons.  Click on each photo to see its original.)

Ticking, whirring, grating, droning.  August is Bug Noise month.

Nature is loud right now.  During the day there’s a chirping and buzz-saw whine; at dusk, a grinding, droning chorus and a faint whirring sound.  Marianne Atkinson, who lives in Clearfield County, Pennsylvania, says “a loud, 2 part, harsh sound, repeated quickly, sort of like saying hello” starts up at twilight near her home.

What makes these sounds?

I searched the web for an answer and found this helpful page on the Music of Nature website:  the songs of 20 common insect species. 

Just for fun I listened to a few of the recordings and they solved an old mystery. 

Years ago, before Duquesne Light cut back the trees across the street, we heard a ticking sound at night in the summer.  The bug that made that sound is pictured above, a greater angle-wing katydid.  It actually made two mystery sounds:  the ticking and a periodic “dzit.” 

When we had the greater angle-wing katydid in our neighborhood I never saw it among the leaves.  If it had perched on a lawn chair, as this one did in Texas, I would certainly have noticed it!

Listen to the Songs of Insects and you might find the one that puzzles you.

(photo in the public domain from Wikimedia Commons.  Click on the photo to see the original.)

Three weeks ago I hiked along Hell Run down to Slippery Rock Creek and paused by the stream to eat lunch.

It was cooler by the creek so I stayed a while and watched the water striders patrolling the quiet pools.  Eventually a dragonfly flew over the creek, then hovered above the riffles and began to bounce her tail in the moving water over and over again.  It looked like she was riding a pogo stick.

What was this?

My bug knowledge is almost non-existent so I asked Chuck Tague and he put me in touch with Ben Coulter.  Ben told me I saw the typical ovipositing behavior of a female spiketail. Though I couldn’t describe the bug well enough to identify the species, it was in the Cordulegaster genus.

Yes, the dragonfly was laying eggs.

To show you how strange this looked I found two videos on YouTube.  The first, above, is a good illustration of the pogo-stick behavior even though the bug in the movie is not native to North America.  (The golden-ringed dragonfly lives in Britain.)

The second, below, is an award-winning video I’m sure you’ll enjoy — and it shows dragonflies native to Pennsylvania.

David Moskowitz studied Tiger spiketail (Cordulegaster erronea) mating behavior by suspending fake female look-alikes from fishing poles to see if they could attract a mate.   When the fake females did not bounce, the males were uninterested.  When the “females” looked as if they were ovipositing, the males tried to mate with them.  Notice how the male rushes over and grabs her!

Turn up your speakers; you’ll like the music.  (Sorry about the ad a few seconds into it.)

And don’t miss David Moskowitz’ Bug Addiction website.

(videos from YouTube)

This amazing creature with beautiful orange and yellow accents is a regal or royal walnut moth (Citheronia regalis), the largest moth north of Mexico with a wingspan of up to six inches. 

He didn’t always look like this. 

As a caterpillar he molted five times, becoming bright green with scary horns and “about the size of a large hot dog,” according to the Bug Guide.  He preferred to feast on hickory and walnut trees, earning him the name hickory horned devil.

In his final instar, when he’d eaten his fill, the hickory horned devil turned a beautiful turquoise color and searched the ground for a suitable place to burrow 5-6 inches under the soil and spend the winter pupating.

Marcy Cunkelman captured this process, beginning in August last year, when the man who services her furnace brought her a hickory horned devil.   She marked the place where the caterpillar burrowed and brought him above ground at various stages to see what he looked like. 

He shed his skin, turned a beautiful color, then became dark and emerged as a moth early this summer. 

Here he is just before he flew away, destined to live only a week.  Regal moths have no mouths and cannot eat.  Their only purpose is to reproduce.

Click on Marcy’s photo to watch the metamorphosis.

(photos by Marcy Cunkelman)

I was doing the laundry the other day when I picked up a jug of detergent from the basement floor and this critter dropped off the underside onto our gleaming white washing machine.

He was not happy to be exposed in a high, bright place so he ran to the edge of the machine and looked down. 

I was startled (I think I screamed) but I got a good look at him before I killed him.  (Did I tell you I hate bugs?)  His long flat body and curved pincers impressed me so much that I looked him up.

This is a male earwig!  

Despite the name, earwigs do not crawl into human ears.  They’re nocturnal insects who spend the day hiding in dark damp crevices and come out at night to eat living and dead plants and animals, including insects.  I should probably be grateful to have a few patrolling my basement.

Earwigs are really successful bugs.  They first appeared in the late Triassic period 208 million years ago and they are still around today.  For comparison Dippy the Dinosaur (Diplodocus carnegii) lived for about 5 million years in the late Jurassic period, 154-150 million years ago.

Part of earwigs’ success may be due to this unusual trait:  Though they are not social insects, the mother earwig guards her eggs and babies.  She continuously cleans the eggs to remove fungi, monitors their warmth and protects them from predators.  When the eggs hatch she stays with her young until their second molt. 

There are 1,800 species of earwigs on earth but they don’t survive winter outdoors so there are only 25 species in North America.  The European earwig (Forficula auricularia) was introduced from Europe in 1907, the same year my house was built. 

After all this time I finally noticed my house is home to this prehistoric bug.

(photo by Scott Hussey via Shutterstock.com)

This dragonfly doesn’t perch like this for fun.  His pose is a threat display.

This is a male Common Whitetail (Plathemis lydia), a showy dragonfly with a white pruinose abdomen and clear black-striped wings. 

Common Whitetail males are highly territorial.  They live near ponds, marshes and slow moving rivers where they defend 10 to 30 yards of the water’s edge and conspicuously chase away all other males.  When they’re not chasing they pose like this to let the others know they mean business. 

Their white pruinose backs are the warning sign.  Pruinose refers to the dusty, frosted appearance caused by a pigment that covers the insect’s ”skin.”  In nature, pale-colored pruinescence often reflects ultraviolet light.  If so, this bug probably glows in sunlight.  I wish I could see it!

Female Common Whitetails look quite different because their tails aren’t white, a feature that probably protects them from male aggression. 

Watch near water and you’ll see the males patrolling.  Try to find the females too, even though they’re not so flashy.  

I’m happy when I see them.  These dragonflies eat flying insects, including mosquitoes!

(photo by Chuck Tague)

Have you ever had a cloud of bugs fly around your head, yet when you wave them away they’re back in an instant?  The bugs aren’t biting but they will not leave.  What’s going on?

It’s a mating ritual.

In some insect species the winged adults congregate in a swarm to meet each other.  It’s the bug version of the bar scene.

Each bug flies around in the crowd, looking for a member of the opposite sex.  The individuals break away to go off and mate yet the cloud stays put.  To do this they use a tall object as a reference point — a swarm marker – to maintain their position.  We see this in the fall with flying ants at hawk watches.  The mountain is their marker.

Anything can be a swarm marker.  In early June, thousands of mayflies swarm at Lake Erie in Cleveland using buildings, people and trees as their markers.  They look scary but they’re harmless — and messy when they leave the swarm to mate on windows, walls, cars … everything!

So it’s not that the bugs love you.  It’s just that they’re using your head as a swarm marker.  Walk under a tree with low branches and they’ll leave your head to use the tree.  Good luck leaving them behind when you walk away.

Of course, this doesn’t work with mosquitoes.  Mosquitoes do love you!

(photo by Anton Gvozdikov/Shutterstock.com)

p.s. For more information about midge swarms, see page 9 of this document from Nature.org.

But it sure looks like one.

On Wednesday I blogged about Sundrops and included a photo of a flower with a honeybee on it — or so I thought.  Fortunately Monica Miller pointed out my mistake (which I corrected) and I learned something new.

This bug is a honeybee mimic who looks so similar he’s often mistaken for one.  He’s the same size as a honeybee and has a dark brown body with orange-yellow patches covered in short hairs.  He hovers like a bee and he feeds on nectar. 

But he’s a drone fly, a member of the family Syrphidae also known as hover flies.  This one is in the genus Eristalis and is probably the most common species, Eristalis tenax, but drone flies are so hard to tell apart that it’s beyond the capabilities of someone like me who only just learned they aren’t bees!

How do you tell the difference between a drone fly and a honeybee?  The drone fly is a “true fly” so he has:

• only one pair of wings
• large eyes (which happen to have a row of upright hairs on them)
• no waistline (honeybees have a narrow waist)
• inconspicuous antennae
• and no sting!

In the larval stage you’ll never mistaken a drone fly for a honeybee.  Drone fly larvae live in stagnant water and feed on decaying organic material.  The water they prefer is so low in oxygen that they have tubes on their rear ends that they raise to the surface to breathe.  This gives them the nickname rat-tailed maggots.  Eeeeeew!  They like manure pits. 

Drone fly adults are good pollinators so perhaps that’s why they were introduced into North America around 1875. 

I don’t know how they got here, but I do know I prefer to meet them as adults.

(photo by Alvesgaspar from Wikimedia Commons.  Click on the photo to see the original)

Right on time, the lightning bugs are back in Pittsburgh.

Lightning bugs, also called fireflies, are beetles that spend the majority of their lives as larvae.  We don’t really notice them until they become adults and fly around flashing their luminescent abdomens.  In Pittsburgh they begin doing this in June(*).

One species, Photuris pennsylvanica, happens to be the State Insect of Pennsylvania.  Its larvae hibernate underground or under bark all winter and spend their days there too, only emerging at night to feed on soft-bodied insects, worms and tiny snails.   The larvae can glow, but they do not fly.

The adults are not as predatory because their primary goal is to find a mate which they do by flashing.

The females flash “come here” from a prominent perch while the males fly around looking for a responsive female — and flashing their signals as well.  When they find each other, they mate.

For us, fireflies are pure joy.  They don’t sting or bite and they create beautiful light shows on summer evenings.

I might not be wild about bugs but I do like fireflies!

p.s. If you want to see lightning bugs in your yard, don’t use pesticides on your lawn and garden.

*p.p.s:  Readers in nearby counties have been seeing lightning bugs since Memorial Day.  I didn’t notice them in the city until last night.  Is there a difference in timing or was I not paying attention?

(video from YouTube)