The white pine sawfly is not a native species of Maine. Doug Hitchcox photo

As we enter late summer, there are hundreds of cool insects which should have you on the lookout. In the evenings, I love to hang a bedsheet out with a light on it and see the dozens of unique moths I can attract; the days can be spent checking blooming wildflowers for a variety of pollinators. We are getting the seasonal influx of questions about all the “bugs” that are bugging people, so I wanted to point out some of the “good” and “bad” insects that are around right now.

First, let’s talk about sawflies. As adults, these are more recognizable as flies, in the order Hymenoptera with their membrane wings, but most people encounter their larval stage, in which they are more likely to be mistaken for a caterpillar. Of the 80-plus species of sawflies in Maine, the one most commonly encountered is the unsurprisingly non-native and appropriately named introduced pine sawfly (Diprion similis). These are typically found feeding on white pines, but as they mature, prior to forming a pupae, they will drop to the ground and often land on porches or vehicles where people encounter them, sometimes in large numbers. Most of the photos we get of these invasive sawflies show them in a defensive posture, lifting up their abdomen and two or three sets of legs. When dozens of the larvae do this all at the same time, it’s a pretty impressive sight.

The native elm sawfly is easily identified. Doug Hitchcox photo

Another sawfly frequently encountered is the native elm sawfly (Cimbex americanus). The largest species of sawfly in Maine, it has a dark dorsal stripe on a typically pale whitish body, making it a very detectable species. Despite being defoliators, they rarely will do enough damage to harm a tree but will make for a high-protein food source for birds and other animals, so leave them be if you can.

Switching from the sawfly larvae that just look like caterpillars, there are some actual caterpillars to look for right now. A common species we are often asked about in August is the fall webworm (Hyphantria cunea), which, after overwintering as a pupae, will emerge as an adult moth next summer. These are often mistaken for other unfavorable species that make large web nests, like browntail moths, but the fall webworm is actually a native species! Interestingly, they’ve been accidentally introduced in other countries where, without the natural predators and controls, they’ve come to be considered a pest, but here in Maine they are a great part of the ecosystem.

Another fun and fuzzy group of caterpillars we’re hearing a lot about just now are tussock moths. Most of these are named for their host plant, where you are going to find feeding larvae, but we also find these furry-looking caterpillars as they wander to wintering sites before forming a chrysalis. Most people will find milkweed tussock moths (Euchaetes egle) when looking for monarchs on milkweed, and their distinctive black and orange stripes with a few white tassels give them a very tiger-like look.

Despite the name, the hickory tussock moth is a fairly distant relative, but is also a common species you’ll see going into the fall. Its mostly white fuzz with a black line down the back is fairly distinct. Both moths fall into the large family Erebidae, which includes many showy moths and familiar caterpillars like the isabella tiger moth (Pyrrharctia isabella), more commonly known as the wooly bear.

I hope this serves as a quick introduction to some of the caterpillars and lookalikes that you are likely to find in the fall. I recommend downloading iNaturalist or Seek, both great apps that can help you identify many of the living things you encounter. Too often, people have a gut reaction to squish or otherwise remove many of the insects we find in our gardens or around our homes. I’d like to encourage everyone to try learning about these species and the roles they play in our ecosystem. While some insects can overwhelm host plants, and some produce hairs that create rashes for humans, most are not harmful to you or the host plant and may be beneficial to native wildlife. Before we “leave the leaves” this fall, start searching for these insects on all the native plants in your yard!

Have you got a nature or wildlife question of your own? It doesn’t have to be about birds! Email questions to ask@maineaudubon.org and visit maineaudubon.org to learn more about birding, native plants, and programs and events focusing on Maine wildlife and habitat. Doug and other naturalists lead free bird walks on Thursday mornings, 7 to 9 a.m., at Maine Audubon’s Gilsland Farm Audubon Sanctuary in Falmouth.