Category Archives: Insects, Fish, Frogs

Hope For What We’ve Lost

Fall colors of white ash, 26 Oct 2017 (photo by Kate St.John)
Fall colors of white ash, 26 Oct 2017 (photo by Kate St.John)

Two weeks ago I lamented that fall color is disappointing this year but I should have waited.  The trees in Schenley Park looked better last week with red maples, yellow hickories, and this small tree reminding me of what we've lost.

Those pale green, yellow, orange and violet leaves are on a small ash tree whose trunk diameter is too small to be plagued by emerald ash borer ... and now I've found out why.

Before the emerald ash borer (EAB) invasion, mature ash trees added pastel violet to the splash of color on our hillsides but now only the saplings are left.

Just across the trail from the ash sapling stands a mature ash that's alive, though struggling.  Some upper branches have died back and there are sucker branches below them.  An old emerald ash borer hole shows what the mature tree was dealing with.

White ash tree with emerald ash borer hole in bark (photo by Kate St. John)
White ash tree with emerald ash borer hole in bark (photo by Kate St. John)

The old tree is alive because it received insecticide treatments during the height of the EAB invasion from a program of the Pittsburgh Parks Conservancy and the City of Pittsburgh.   Beginning in 2011, 158 specimen ash trees were treated in the city parks.  This one is #76 according to the metal tag.

White ash tree with tag indicating it is treated for emerald ash borer (photo by Kate St. John)
White ash tree with tag indicating it is treated with insecticide for emerald ash borer (photo by Kate St. John)

Years later it appears that emerald ash borer numbers have dropped and it wasn't because we used insecticides.

Scientists working on EAB biological control in Michigan found that many factors contributed to the emerald ash borer population collapse there.

"Woodpeckers, native and introduced parasitoids, intraspecific competition, disease, innate tree defenses, and reduced ash abundance contributed to the collapse of EAB populations."

Notice that woodpeckers are at the top of the list!

Second on the list are four tiny parasitic insects that kill emerald ash borer larvae.  Two native insects target emerald ash borers through the thin bark of saplings and at Michigan study sites scientists introduced two more parasitic insects from China, the emerald ash borer's homeland, to get through the bark of mature ash trees.

Thanks to the hard work of scientists and arborists we may hope that our ash saplings will grow into mature ash trees.

Read more about ash tree biological controls at this U.S. Forest Service webpage.

 

(photos by Kate St. John)

An Insect Surrounded

Gall on black walnut leaf, 2 Nov 2017 (photo by Kate St.John)
Gall on black walnut leaf, 2 Nov 2017 (photo by Kate St.John)

When an insect laid its egg on this black walnut leaf, the leaf responded by surrounding it to wall it off.

That's exactly what the insect had in mind.  The wall makes it safe.

Now that the leaf has fallen from the tree, I wonder what will happen to the insect.

p.s. I have no idea which gall this is.  Do you know?

 

(photo by Kate St.John)

Autumn’s Flying Ants

Citronella ant, Lasius interjectus, with wings (photo by Alex Wild via SmugMug)
Citronella ant, Lasius interjectus (photo by Alex Wild via SmugMug)

On warm fall days look up and you might see swarms of flying ants.  Flying high, they're annoying at hawk watches.  What are these ants and what are they doing?  The answer is more interesting than you might think.

Flying ant swarms are the mating dance, the nuptial flight, of winged male ants and virgin queens.  Each species has its own time of year for mating.

If you've never seen a swarm here's what it looks like, filmed at a tall grass prairie in Nebraska (20 seconds).

 

The ants are so preoccupied with mating that they don't pay attention to what's nearby and are easy prey for migrating dragonflies, cedar waxwings, and even ring-billed gulls.

 

Don't worry. The swarms are not termites. Termites make their nuptial flights in the spring and, if you look closely, they're different from ants.  Ants have pinched waists and "nodes" at their waistlines. Termites do not.  Here's a visual comparison -- not to scale -- of fire ants on the left and eastern subterranean termites on the right.

Compare body shape of two wingless insects: fireants and eastern subterranean termites (photos from Wikimedia Commons)
Compare body shape of two wingless insects: fire ants and eastern subterranean termites (photos from Wikimedia Commons)

 

In autumn in Pennsylvania the swarms are sometimes citronella ants, Lasius interjectus (shown at top) or Lasius claviger, described here by Penn State Cooperative Extension.  The name comes from their lemon smell when threatened or crushed.

Citronella ants spend their whole lives underground except when they emerge to mate.  They're actually "farmers" who tend their livestock -- aphids -- and harvest the aphids' honeydew.  This video describes a citronella ant colony.

 

After the nuptial flight the male ants die and the fertilized queens shed their wings.  They don't just shed them, they yank them off!  Watch this citronella ant use two of her six legs to pull off each wing (7 seconds).

And then the queen walks off to find an underground place to nest.

There are so many ant species that it takes an expert to identify them.  If you know which ones fly at the Allegheny Front Hawk Watch in September, please let me know.

 

(photo credits: citronella ant photo Lasius interjectus by Alex Wild via SmugMug, composite photo of fire ants and eastern subterranean termites from Wikimedia Commons.  video credits: Ant swarm in Nebraska by Evan Barrientos on YouTube. Citronella ants by Chris Egnoto - The Naturalist's Path on YouTube.  Ant yanking off its wings by David Shane on YouTube)

Caterpillars As Transformers

Woolly bear caterpillar, Pyrrharctia isabella (photo from Wikimedia)
Woolly bear caterpillar, Pyrrharctia isabella (photo from Wikimedia)

On Throw Back Thursday:

More amazing than a Transformer toy that changes from a robot into a spaceship, this woolly bear caterpillar will wrap himself in a cocoon and spend the winter transforming into a moth.

So will this hickory tussock caterpillar ...

Hickory Tussock Moth (photo by Kate St. John)
Hickory Tussock Moth (photo by Kate St. John)

... and this Promethea caterpillar.

Caterpillar of the Promethea moth, twig held by Ramona Sahni (photo by Kate St. John)
Caterpillar of the Promethea moth, twig held by Ramona Sahni (photo by Kate St. John)

Odd and ugly caterpillars become beautiful -- or boring -- moths.

Who becomes what?

Chuck Tague's 2010 guide to caterpillars and moths has the answer in photographs.  See A Game of Cat and Moth: caterpillars and what they become.

 

(photo credits: wooly bear caterpillar by Christopher Jones from Wikimedia; click on the photo to see the original. hickory tussock moth caterpillar by Kate St. John. promethea moth caterpillar by Kate St. John)

 

Leaf Miner on Coltsfoot

Leaf miner on coltsfoot (photo by Kate St. John)
Leaf miner on coltsfoot (photo by Kate St. John)

Autumn is a good time to look for unusual leaves. They used to be boring until something happened to them.  Like this.

There's an elaborate squiggle on this coltsfoot leaf (Tussilago farfara) made by a leaf miner, an insect larva that makes a path as it eats within the leaf tissue.  Eventually the larva settles down to pupate and the path comes to an end.  When the adult insect hatches it leaves a hole.

What makes these lines?  I had no idea until I googled "leaf mine on coltsfoot"and found the answer.  A blogger at Nature Post collected similar coltsfoot leaves, put them in jars, and waited for the adult insects to appear.  It turns out his leaf mines were made by tiny moths called Phyllocnistis insignis.

See more leaf mines and a photo of the adult moth in his Nature Post from October 2013:  A Little Scientific Discovery.

 

(photo by Kate St. John)

Webs in the Trees

In the spring we saw tents in the trees.  Now we see webs. Though similar in concept, the structures aren't made by the same species.

The springtime tent, located in the crotch of a tree, is made by eastern tent caterpillars (Malacosoma americanum) who emerge from their tent to eat young leaves as they unfurl.  The webs, located on the branches, are made by fall webworms (Hyphantria cunea) who hide in the web and eat leaves that will fall off in a month or two.

Since late summer female moths have been laying egg masses on deciduous trees.

Fall webworm moth (photo from Wikimedia Commons)
Fall webworm moth (photo from Wikimedia Commons)

After a week the eggs hatch into tiny caterpillars who build a web to completely enclose themselves and their food.  As they eat, they build the web larger to enclose more leaves.

Fall webworms avoid coming out of the web until they're ready to pupate. Then they hide their cocoons under flaps of bark to overwinter and emerge next year.

Though the webs look ugly they don't harm the trees because the leaves will drop soon anyway.

See webworms in action in the video above from The Capitol Naturalist in D.C.  Read more in this vintage article from 2011:  Coming Soon To A Tree Near You

 

(photo of fall webworm moth from Wikimedia Commons; click on the image to see the original)

In Hot Water

Two men holding an Atlantic sailfish caught off the coast of Port St. Lucie, Florida (photo from Wikimedia Commons)
Two men holding an Atlantic sailfish caught off the coast of Port St. Lucie, Florida, 2010 (photo from Wikimedia Commons)

The warming ocean has been in the news lately as the most powerful Atlantic hurricanes ever recorded -- Harvey's rain and Irma's wind -- slammed into Texas, the Caribbean, and Florida.  The ocean is hotter now than any time since record keeping began in the 1880's and, though hotter water doesn't cause hurricanes we've learned it makes them worse.  Uh oh!

There's another sign the ocean is warming.  Fish are on the move.  A wide variety of species including sole, haddock, herring, and black sea bass have left places too warm for them and migrated to cooler water.

For example an enormous Atlantic sailfish (Istiophorus albicans), normally off the coast of Florida above, was caught in the Cape Cod Canal in August 2013.  It was the first Massachusetts record.

It's not just temperature that makes fish move.  Warm water has less oxygen, so it's harder to breathe, and more carbon dioxide so it's more acidic.  Acidic water holds less calcium carbonate, the building block of sea shells including those of tiny copepods.  With fewer tiny organisms there's less food all the way up the food chain.

Fish swim away from these "deserts" but some animals can't move very far. Think of lobsters, now gone from Long Island Sound.

The changes in species affect both fishermen and nesting seabirds.  The old catch limits refer to fish that can't be found because they've moved north, and baby puffins starve because the new species are too big for them to swallow.

From more powerful hurricanes to fish leaving home, we're in hot water!

 

Read more in this article from Yale e360: Feeling the Heat: How Fish Are Migrating from Warming Waters

(photo from Wikimedia Commons; click on the image to see the original)

The Zig Zag Web

Yellow garden spider female with prey (photo by Kate St.John)
Yellow garden spider female with prey, Virginia Beach, 5 Sept 2017 (photo by Kate St.John)

Last week in Virginia Beach my mother said, "Come see my spider."  We stepped out the front door and there she was, an impressive yellow garden spider with a zig zag web.

Yellow garden spiders (Argiope aurantia) are very common orb weavers but we rarely notice them until late summer when the females have reached full size, about an inch long.   At this point their webs are also large with conspicuous vertical zig zags(*) giving them this alternate name in Virginia: the sewing machine spider.

My mother's spider hid behind her web which in turn was camouflaged by the light colored brick behind it.  (Click here to see a more obvious zig zag.)  In these photos the spider is packaging prey in gauze or perhaps eating it.

Yellow garden spider with prey (photo by Kate St.John)
Yellow garden spider with prey (photo by Kate St.John)

My mother pointed out a smaller web nearby with a smaller spider in it, only 0.2 to 0.3 inches.  It was the male who will eventually come courting, but he has to be very careful and quick.  His goal is to deliver both sperm packages without being attacked.  After delivering the second one he dies a natural death.  Then the female eats him.

Soon the female will lay 500 to 1,000 eggs in a small brown sac which will overwinter and hatch in early spring.  The tiny spiderlings are cannibals, too, but those who survive will play out the same story next year.

If you find a yellow garden spider you can enjoy it in peace.  Even though the females are large, they won't bite unless you grab them (egads!) and their venom is harmless to humans.

Read more about these and other Pennsylvania native spiders in this fact sheet from Penn State.

 

(photos by Kate St. John)

(*) The zig zag is called a stabilimentum.

How Do You Know It’s A Moth?

Antennae of an Agreeable Tiger Moth (photo by Chuck Tague)
Antennae of an Agreeable Tiger Moth (photo by Chuck Tague)

What's the difference between a moth and a butterfly?

The best clue is their antennae.

Moths have feather-like antennae with many branches.  Butterflies have smooth antennae with a knob at the end.

The feathery antennae above are on an Agreeable Tiger Moth photographed by Chuck Tague.  Yes, the moth is agreeing to have his picture taken and yes, that's really his name!  Agreeable Tiger Moth (Spilosoma congrua).

The knobs on the antenna below are on a Pearl Cresent butterfly (Phyciodes tharos).

Pearlcresent butterfly (photo by Kate St. John)
Pearlcresent butterfly (photo by Kate St. John)

 

For more differences between moths and butterflies see this vintage article from August 2010:  How Do You Know It's a Moth

 

(photo of Agreeable Tiger Moth by Chuck Tague. photo of Pearl Crescent Butterfly by Kate St. John)

Green Eggs On Nettle

Green eggs on stinging nettle leaves (photo by Kate St.John)
Green eggs on stinging nettle leaves (photo by Kate St.John)

Today, a quiz.

I found green eggs on stinging nettle on August 9 at Wolf Creek Narrows, Butler County, PA.

Are they eggs or something else?

And who laid them?

Post a comment with your answer.

I'll reveal their identity later today.

 

THE ANSWER:  29 August, 3:15pm
This was a tricky quiz because the structures really do look like eggs. I thought they were butterfly eggs but they are too smooth. The likely butterflies lay very wrinkled eggs.  For instance, click here to see the eggs of the small tortoiseshell butterfly.

Mary Ann Pike correctly identified the green "eggs" as nettle galls of (probably) Dasineura investita.  The galls are the plant's defenses against the larvae inside them.  The larvae are from midges so tiny that I can't find photographs of the adult insects though these three photos may give you an idea.

Caterpillars of the Sordid Hypena moth (Hypena sordidula) eat these galls.  Click here to see it.

 

(photo by Kate St. John)