20 August 2022

Last weekend in Lower Frick Park Charity Kheshgi and I saw thousands of caterpillars and a lot of frass dropping from the trees above the pedestrian bridge over Nine Mile Run (pictured above).

Many insects are specialists, consuming a single plant family or genus during in their larval phase. If you can name the plant the caterpillar is eating, you can narrow down the identity of the bug.

Using that method I tried to name the leaves the caterpillars were skeletonizing (eating habits are another clue!) but most were too damaged to identify. Eventually I found a few intact elm-like leaves.

The photo match for “larvae that skeletonize elm leaves” included an adult form matches the golden yellow mystery beetle I saw this summer in Frick Park. These are larger elm leaf beetles (Monocesta coryli).

The “larger” beetle is a pretty big bug, shown for scale on someone’s hand in this photo by Bill Sweeney embedded from bugguide.net, and its color varies. Click here to see an orange one.

Here’s what it will do next.

There is only one generation per year. Eggs are laid in the spring in “hard yellow crusty” masses of 24 to 58 eggs on the undersides of elm leaves. They hatch in about two weeks.

The newly eclosed larvae are about 3 mm long and greenish-yellow. They are gregarious for three to four days and feed on leaf surfaces before dispersing. The mature larvae crawl down the tree and undergo a wandering phase for a few days before entering the ground, where they remain until pupation the following late winter or early spring. Pupation lasts about a month and adults begin emerging in April. Adults are active from April until early August, with most records from June to July. Both adults and larvae exude an orange, presumably defensive, fluid when disturbed.

— Univ of Florida Entomology: Larger Elm Leaf Beetle

So why are these not caterpillars? Because the larvae of beetles are called “grubs.”

(photos from bugwood, from bugguide and by Kate St. John, click on the captions to see the originals)

14 August 2022

At this time of year you’ll often see black and orange bugs crawling on milkweed seed pods. These are milkweed bugs, large and small, that consume the seeds by injecting saliva through the pod shell into the seed beneath and sucking out dissolved seed matter. Though the “large” and “small” bugs look very similar they are not the same species.

The Large Milkweed Bug – Oncopeltus fasciatus 

Large milkweed bugs are orange and black with a black horizontal band across the middle of the back. In this species you can tell male from female. On the underside of the bug, the 4th abdominal segment is a black stripe on males and two black spots separated by orange on the females. Click here for a photo of two mating: female at top, male at bottom.

O. fasciatus overwinter as adults and are so easy to raise that they are used in labs and sometimes raised at home. To avoid cold winters the northern populations migrate!

The Small Milkweed Bug – Lygaeus kalmii

The orange and black “small” milkweed bug (Lygaeus kalmii) has a different pattern on its back: a black heart in the center and two black patches on either side (see top right photo).

Juveniles are dependent on milkweed but when milkweed is scarce the adults become scavengers and predators that, according to bugguide.net, have been reported feeding on honey bees, monarch caterpillars and pupae, and dogbane beetles.

L. kalmii range across the US and Canada except for the southeastern US. They overwinter as adults by producing antifreeze in their bodies to survive the cold.

The False Milkweed Bug – Lygaeus turcicus

Like the monarch butterfly, the orange and black color of milkweed bugs warns predators that they are toxic. Viceroy butterflies mimic monarchs so they won’t be eaten. “False” milkweed bugs (Lygaeus turcicus) mimic small milkweed bugs (L. kalmii) for the same reason.

The black pattern on the “false” milkweed bug is slightly different. Instead of a black heart it is a V that seems to overlay the black beneath it much like the W overlays the V in West Virginia University’s logo.

The “false” bug also has black parentheses around the V. Compare the two below.

The “false milkweed bug” could be called the “false sunflower bug” because that’s what he eats — the seeds of Heliopsis helianthoides.

(photos by John English and Kate St. John, WVU logo decal for sale at Amazon)

31 July 2022

When the highly invasive spotted lanternfly (Lycorma delicatula) was first discovered in western Pennsylvania in January 2020 it was a non event for most of us. We knew the bug was plaguing eastern Pennsylvania and that Allegheny County became a lanternfly quarantine zone, but for two years most of us never saw one. That changed this summer when many Pittsburghers found them in their own backyards.

Frank Izaguirre’s experience in Oakland is typical. The first one appeared on 17 July but within ten days the number of bugs had grown so fast that finding and killing them, as recommended by the PA Dept of Agriculture(*), became a daunting daily chore.

Annie Quinn noticed them in a park and enlisting her kids to squash them on the ground. Then she looked up and saw hundreds and hundreds coating the upper branches of the trees. “Kids, this problem is much bigger than we are.”

Indeed! I saw hundreds (thousands?) on the North Shore near the Carnegie Science Center on Tuesday 26 July.

And it’s going to get worse before it gets better.

Julie Urban, an associate professor of entomology at Penn State, said residents of the area will see a lot more lanternflies in September.

“They’re starting to emerge as adults about now and then when they start to mate more heavily you’re going to see a lot more in the first couple weeks of September,” said Urban. “That’s just when they’re more active. So, be ready for that.”

— Trib-Live: Spotted Lanternfly numbers way up in Allegheny County

Since each female lanternfly lays an egg mass containing 30-50 eggs, the population grows exponentially every year: 1 > 50 > 2,500 > 125,000 > 6.2 million!

It took just 2.5 years to go from “What’s the problem?” to “Oh my gosh!”

There is no way we can squash them individually. However there are easy ways to passively kill them in our yards. Three years ago a girl in New Jersey came up with a very inexpensive and effective trap.

Other inexpensive do-it-yourself traps are described at these YouTube links: A simple tulle trap, the simplified hoop trap and an elaborate v2 Trap that requires tools. In any case if you make a trap, use netting not glue. Glue tape indiscriminately kills bees, bats and small birds that try to feast on the trapped bugs.

This is our first Summer of the Spotted Lanternfly in Pittsburgh, but it’s not the last.

Read more about the current outbreak at Trib-Live: Spotted Lanternfly numbers way up in Allegheny County.

(*) The PA Dept of Agriculture is encouraging anyone who sees a spotted lanternfly to kill it and report it online here or by calling 1-888-422-3359.

(photos by Frank Izaguirre, Kate St. John and from Wikimedia Commons)

p.s. On 5 August 2022 one landed on my bedroom window on the 6th floor of a highrise. Uh oh!

21 July 2022

When you “Vote with your feet” you show your opinion by leaving an organization or by no longer supporting, using, or buying something.

Butterflies vote with their feet — literally — for the opposite reason. They decide to stay.

After mating with a male, the female butterfly must go in search of a plant on which to lay her eggs. Because the caterpillars that will hatch from her eggs will be very particular about what they eat, she must be very particular in choosing a plant. She can recognize the right plant species by its leaf color and shape. Just to be sure, however, she may beat on the leaf with her feet. This scratches the leaf surface, causing a characteristic plant odor to be released. Once she is sure she has found the correct plant species, she will go about the business of egg-laying.

— University of Kentucky: All About Butterflies

Sometimes this activity is called “tasting” the plant. Learn more and see photos of butterflies making the “stay or go” decision in this vintage article.

(photo by Kate St. John)

17 July 2022

Have you noticed small white caterpillars this month, suspended on invisible threads from the tree canopy and swinging in the breeze? You might see only one but there are others nearby dropping from the same tree. These are hickory tussock moth caterpillars (Lophocampa caryae) traveling from their natal leaves.

Here’s what one looks like. Why is it climbing? Read on.

Last month the caterpillars were just a cluster of eggs, laid by their mother on the underside of the leaves they prefer: hickory, walnut, pecan or blue-beech. Their parents found each other by unusual means.

Arctiids have a thorax that comes equipped with a sound-producing organ. The moths “vocalize” to attract mates and to defend against predators, emitting ultrasonic clicks [>20,000 Hz] that advertise their identity. Because an animal that is able to make sound probably needs to be able to hear it too, Arctiids have “ears,” also located on their thorax.

— paraphrased from The Bug Lady’s Hickory Tussock Moth account

The parents die after reproducing but the young live on. When they hatch the caterpillars are toxic so they safely feed in a crowd, eating leaf tissue between leaf veins and skeletonizing leaves.

After they’ve eaten everything in sight they have to move on so they spin out an invisible thread and swing to another branch or tree. The caterpillar in my video had missed the other vegetation and was hanging over a wide gravel road. Perhaps he could see nothing green below so decided to climb the thread back up to the trees.

Read more about their life cycle in Bug Lady’s article Hickory Tussock Moth.

p.s. Did you know that National Moth Week is only 6 days away? 23-31 July 2022.

Help map moth distribution and life history. Attend or start a National Moth Night event (called “mothing”) to contribute scientific data about moths.  Join friends and neighbors to check porch lights from time to time or set up a light and a white sheet to see what’s in your own backyard.

14 July 2022

Though daddy longlegs or harvestmen (Opiliones) resemble spiders they are not even closely related to them. Harvestmen are harmless and have many characteristics that set them apart from spiders including:

• A fused body that appears to be 1 segment. Spiders have a “waist.”
• A single pair of eyes (2) at center-front. Spiders have four pairs of eyes (8).
• Cannot make silk. Spiders make silk and spin webs.
• Cannot regrow a leg that is lost. Spiders can regrow legs.
• No fangs or venom. Spiders have both.
• Eat solid food. Spiders have to liquefy their food, then suck it in.

Harvestmen are members of the class Arachnida that includes spiders, scorpions, ticks and mites. Their closest relatives might be mites, though this is in dispute.

Ironically, harvestmen are sometimes plagued by mites, as shown above and described in this vintage article:

Learn more about harvestmen in this 4-minute video. You may want to watch it more than once. The narrator speaks quickly!

(photos from Wikimedia Commons; click on the captions to see the originals)