Here are four anterior close-ups Pyractomena borealis. The telescoping head allows the larva to inject (via curved, hollow mandibles) a numbing agent into snails that have retreated inside their shells. The antennae and maxillae are also partially retractable. When a larva is done feeding on a snail (or slug or earthworm) it will de-slime all of these parts with the hooked, fingerlike projections of the holdfast organ (pygopod) located on the last abdominal segment. The head is also fully retractible (see previous post). These larvae are extremely active, so really hard to photograph.
Tag Archives: larvae
Pyractomena borealis (Lampyridae) exploring the surface of trees on a warm winter day in February. The third photograph shows how they can retract their head under the carapace like a turtle. At first I thought they might be foraging — they are highly predaceous, and hunt slugs and earthworms (in packs!) by first injecting them with paralytics. But they might have just been looking for a place to pupate, because it’s time for that. Adults will emerge sometime in early Spring to be the first fireflies in the area. The larvae are bioluminescent, too. The hypothesis about why the larvae glow is that it evolved first as an aposematic trait in larvae, warning mice and toads of the presence of lucibufagins, steroidal toxins in the hemolymph. It’s thought that the adult habit of using flashes is secondarily evolved, millions of years after the larvae evolved the ability to glow. The ability of larvae to glow even predates the origin of the Lampyridae, I gather. For more enlightening details, see Branham and Wezel (2003), Stanger-Hall et al. (2007), and Martin et al. 2017.
Here are three types of Chrysopidae (green lacewings) I found a few days ago. One had covered itself with insect parts (and spider web), another with (perhaps) fluff from some wooly homopteran (woolly alder aphids?), and a third with bits of lichen. There’s currently no way (as far as I know) to identify these larvae based on their debris preferences. And it seems likely that there are many undescribed species tooling around right in front of us (e.g.). Like many aspects of natural history, there’s a huge need for citizen scientists to forward information on lacewing larvae to experts — that need is apparently described in this article by Catherine Tauber et al. (Side note: don’t publish “calls for citizen science submissions” in paywalled journals that citizens cannot read.)
Here are photographs of a clump of ectoparasitic larvae I found attached to a small caterpillar. I think they are wasps in the genus Euplectrus (Eulophidae). Females apparently inject hosts with a venom that prevents the caterpillar from molting, thus preventing the caterpillar from shedding the larvae along with the discarded skin. Caterpillar was approximately 12 mm in length. Media, PA.
Here are some photographs of Fulgoraecia exigua, a moth that parasitizes planthoppers during its larval phase. There were dozens of these caterpillars at this location, many of them hanging by silk threads. They look like miniature sheep (a parasite in sheep’s clothing, I guess), and are rather cute, I think. But not for planthoppers, as you can probably guess. When the larvae hatch (earlier in the season) they crawl around and seek out planthoppers to latch onto, then suck their juices and eventually displace their hosts’ wings as the weeks go by. I.e., the planthoppers go about their lives with a caterpillar attached to their abdomens. When it’s done feeding the caterpillar lowers itself to the ground on a silk thread and pupates. I’m going to go back to the spot see if I can get photographs of the pupal form, which looks like a miniature version of the Sidney Opera House, built from the waxy fluff that protected them.