Halysidota tessellaris (Banded Tussock Moth): Identification and Life Cycle

In an earlier post, I wrote about Lophocampa maculata, a moth in the Arctiinae, distinguished by its fuzzy black and yellow larvae. These larvae later metamorphose into beautiful adult moths with a contrasting pattern of alternating bands of warm, muted golden-orange and darker brown markings with a reddish-orange tinge. In this post, I write about Halysidota tessellaris, the banded tussock moth, another moth in the Arctiinae.

*Halysidota tessellaris* caterpillar feeding on a crabapple leaf in late summer.

Identification

Like Lophocampa maculata, the larvae of Halysidota tessellaris are also fuzzy, but they are usually gray to dingy brown with long white and long black tassels. The adult moth, while similar in size to Lophocampa maculata, has translucent yellow forewings marked with slightly darker bands and irregularly shaped block-like cells that form a tessellated pattern. Also, there are two parallel blue stripes on the fuzzy thorax.

Life cycle

Across its range, larvae of Halysidota tessellaris feed on many species of hardwood tree leaves. Among these are box elder (Acer negundo), sweet birch (Betula lenta), ash (Fraxinus spp.), oaks (Quercus spp.), and many others. Adult moths take nectar and are pollinators of milkweeds (Frost, S. W. (1965) Insects and Pollinia. Ecology, 46. 556-558, paywall).

*Halysidota tessellaris*, a worn specimen, but the blue lines are prominent.

Similar species

Adults of the related Halysidota harrisii (sycamore tussock moth) are similar in appearance to Halysidota tessellaris. Where the ranges of Halysidota tessellaris and Halysidota harrisii overlap, genital dissection is necessary to determine the species. Halysidota harrisii larvae, which may be solid white, yellow, orange, or gray, feed exclusively on sycamore (Platanus occidentalis) leaves. The ranges of sycamore and the moth coincide closely.

On my way to the mailbox today

**Four bumblebees are getting nectar from a cluster of joe-pye-weed flowers on a warm, overcast autumn day.**

Essential Guide to Midwest True Bugs by Angella Moorehouse

This just arrived today, and I know it will be so very useful as I venture further into the world of insects. Flower Bugs: A Field Guide to Flower-Associated True Bugs of the Midwest by Angella Moorehouse (2023) is published by Pollination Press LLC, Minnetonka, MN. The Pollination Press web address is www.pollinationpress.com.

This book has 360 pages, lavishly illustrated with beautiful full-color photographs of 160 species of terrestrial true bugs from 25 families and 52 genera. The area covered includes the states of Minnesota, Iowa, Missouri, Wisconsin, Illinois, Indiana, Ohio, and Michigan in the US and Southern Ontario in Canada.

The book includes taxonomic charts that will guide you to family and then to genus, detailed illustrations of bug morphology, their ecology, and a glossary of terms to help you learn and identify true bugs.

Species descriptions are not overly technical, thus making this book more accessible to non-specialists with some background in insect identification. Maps show the range of each species. There are notes on key identifying features, life history, ecology, feeding, and habitat. Descriptions of herbivorous species include lists of plants they consume. Carnivorous species are similarly treated. Not all species receive the same description treatments. Some are represented with photographs.

There seems to be a problem with the index, where some entries do not match the page numbers in the book. Not sure why.

I am loving this book already and will put it to good use identifying the many bug species I have photographed. My first project will be to go through the unidentified species in my files and to re-check previous identifications. After that, I’ll spend many an evening just browsing and waiting for spring and the bugs to return.

Flower flies

Syrphid fly on flower — ***Helophilus fasciatus on Lindley’s aster (Symphyotrichum ciliolatum) looking for pollen and nectar.***

On a warm late summer day if you walk into a field of flowers particularly yellow flowers like goldenrods you might think you have stepped into a swarm of bees or wasps. There is intense buzzing and many small yellow and black insects on the flowers and flying all around you. But despite all appearances these are not bees or wasps at all. They are flies. Syrphid flies, also known as flower flies and hover flies, to be more exact, and there are many species that mimic bees and wasps, a good strategy if you are trying to fend off predators.

Syrphid flies are true flies in the Order Diptera (“two wings”) and Family Syrphidae. Adult syrphid flies feed on nectar, pollen, and sugary secretions from aphids. You can use their love of sweets to attract them with mixture of sugar or honey and water sprayed on surfaces like tree trunks in open areas. When moving about on flowers syrphid flies assist in the pollination of many plant species including crops we grow.

Eristalis transversa on sawtooth sunflower (Helianthus grosseratus). Small hairs on the body of the fly are dusted with pollen. It will probably eat most of the pollen but enough will be spread across the flower head to ensure pollination.

The larvae have more varied diets depending on the species. Some syrphid fly larvae feed on decaying plant matter, damp wood (perhaps for the bacteria and fungus which are more nutritious?), and subterranean parts of plants. Others prey upon aphids, scale insects, thrips, and similar sap-sucking insects and can be beneficial in crop fields and gardens. Some species lurk in ant nests where they disguise themselves with chemical secretions and eat ant larvae.

Syrphid larvae in the tribes Eristalini and Sericomyiin live in muddy stagnant water, even cesspools, where they feed on detritus. A long breathing tube from the anal segment pokes above the water to access the air. This long breathing tube has earned them the name “rat-tailed maggots”.

I recently bought “Field Guide to the Flower Flies of Eastern North America” and have found it very helpful in figuring out species of syrphids that live in my area. The book is well illustrated and includes descriptions and range maps. In the descriptions, the authors have included flowers that species typically visit if known. I have been able with this book to identify three syrphids (Eupeodes americanus, Sericomyia chrysotoxooides, Toxomerus marginatus) that had been in my “unknown” files for several years. And I’ve identified three others I photographed last week (Eristalis dimidiata, Eristalis transversa, Sphaerophoria philanthus).

Below is a small gallery of some of the syrphid flies I’ve seen here over the years.