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)

8 July 2022

When Mike Fialkovich sent me photos of a regal moth laying eggs on a metal fence near his office I wondered if this female was making a mistake. The fence has no food for her tiny caterpillars. What will her larvae eat when they hatch?

The regal or royal walnut moth (Citheronia regalis) is the largest moth north of Mexico with a wingspan of 3.94 to 6.25 inches (females are largest). The adult moth never eats — its only job is to reproduce — but its caterpillars feast on trees including hickories, pecans, black walnuts, sweet gum, persimmon and sumacs.

Normally their lives unfold like this.

Adults emerge in late evening and mate the following evening. Females begin laying eggs at dusk the next day, depositing them in groups of 1-3 on both sides of host plant leaves. Eggs hatch within 6-10 days, and the caterpillars (known as the Hickory Horned Devil) feed alone. Young caterpillars rest on the tops of leaves and resemble bird droppings, while older caterpillars appear menacing because they are very large and brightly colored with red “horns” near the head. Caterpillars pupate in a burrow in the soil.

— Royal walnut moth account at butterfliesandmoths.org

There’s no explanation for why this moth chose a fence. Did it “smell” like a hickory?

Her caterpillars, called hickory horned devils, will need a lot of food to reach this size before they pupate.

It looks like a mistake to me but we’ll have to wait and see.

(photos of regal moth by Mike Fialkovich, hickory horned devil photo from Wikimedia Commons)