Noninsects of 2019

If you don’t like arthropods (insects and spiders and such), get ready to rejoice, because once this post is done, I’ll turn to other subjects. Meanwhile, this is the one that’ll give you the heebie-jeebies for sure. After several posts highlighting the various insects I photographed in 2019, I’m doing a post on non-insect arthropods.

As you might remember, one of the key identifying features of insects is their number of legs: six. So if you see something that looks like an insect and it doesn’t have six legs, then it’s probably not an insect. A millipede is a prime example, because it has not just six legs, but a million.

Just kidding. It’s not really a million legs; it’s usually more like 80 to 100 or so. Interesting fact: they have two pairs of legs for each body segment, not counting the head and tail (which have no legs), and the first three body segments (which have only one pair of legs per segment). As the millipede grows and molts, it adds new body segments. These humble arthropods eat humble fare: lichens, maybe, and decaying vegetation. At least some types of millipedes (usually the ones with bright warning colors) can secrete toxic substances (including cyanide) if they feel threatened. But unless you’re planning on eating one (not recommended), why would anyone threaten a millipede?

Anyway, we found this cute little millipede walking around on our front porch steps in the late afternoon sunshine on March 13; it was a fairly warm evening. It was only about 1¼ inches long. The warming temperatures must have roused it out of its winter torpor.

The next two are spiders. The first is an oddball called a featherlegged orbweaver.

We get these around our yard each year, and I took this photo on June 5. Why do I call it an oddball? Well, first, it just looks odd. The forelegs are typically held straight out in front of the body, though sometimes they hold their forelegs foreword in a Y shape. Either way, they look rather peculiar.

By the way, in the photo above, she is facing downward, her forelegs stretched out straight in front of her, and above her abdomen is one of her egg cases, which is shaped something like a whelk shell. These spiders create a line of these spindle-shaped egg cases, which look a lot like their abdomens, then pose along the line, blending in.

But there’s more. Although they’re an orbweaver (a weaver of orb-shaped webs), they’re not true orbweavers (a member of the Araneidae or typical orbweavers, the family of spiders that build orb webs). Featherlegged orbweavers instead belong to a family of spiders called cribellates, or cribillate orbweavers (Uloboridae), because they possess an unusual sieve-like (perforated) plate called a cribellum, which is positioned at the place where silk exits the spider’s body. This cribellum causes the silk to become hackled—to have woolly fuzzy extensions along its length, instead of being a smooth-sided silky strand. Because the silk is so cottony, it easily snags the legs and other pointy, jagged body parts of insects. They stick to it the way rough dry fingertips snag on polyester fabric.

In fact, this cribellate silk is so good at snagging insects, it replaces the sticky goo that other spiders have on their webs. Also, cribellate spiders have such success with their hackled threads that they do not even have venom; they don’t need it. Not having any venom is a true oddity for a spider. Instead of injecting venom into the prey, they regurgitate digestive juices onto the bound prey, then lap up the liquefying meaty juices. It’s sort of how flies burp up digestive fluids onto their foods, then sop up the goodies.

The other spider I photographed (above) was a longjawed orbweaver, genus Tetragnatha, in family Tetragnathidae. These are also called “stretch spiders,” for the way they rest. Holding the two pairs of forelegs straight forward, and the two pairs of hind legs straight backward, they—with their elongated, narrow bodies—look like little twigs. The “longjawed” part of their name refers to their huge chelicerae. Best not to imagine yourself as a mayfly when you contemplate the hunting of longjawed orbweavers.

They are fascinating spiders that are associated with boat docks and the vegetation around lakes and streams. This longjawed orbweaver built its web among the big tropical plants we keep along the retaining wall of our driveway.

Finally, the other noninsects I photographed were these water springtails (above). Long considered insects, because they have six legs, springtails as a group are now classified separately from insects. They may have six legs, but they aren’t related to insects. I photographed these floating on a pond on a relatively warm day at MDC headquarters, March 23.

Springtails are fascinating! There are all kinds of interesting facts about them, including why they are not considered insects. Here’s another cool fact: water springtails (this species), for instance, can see polarized light—an adaptation for living near water! Do look at my writeup on water springtails on the MDC field guide.