Updates from March 9, 2004

Here's a big water scorpion (no relation to actual scorpions). These guys are just about the most sinister-looking creatures you could find, and what's especially creepy is that they can come up out of the water and fly around, as I learned when one left my aquarium and buzzed my head while I was peeking into the microscope at a mayfly nymph.

I looked at this nymph closely under my crappy microscope. It has truncate as opposed to rounded gills, postero-lateral spines only on abdominal segments 7-9, and oblique crossbars through the center of each sterna, not on the posterior edge like on some of the other Maccaffertium species. As best I can tell from the keys this is either modestum or ithaca and from the distribution maps I've seen I'm guessing it's modestum.

Here's a puzzling nymph. It seemed to have double-banded tibiae, although the second band wasn't very pronounced. It has quite prominent tubercles that definitely aren't black.

I confirmed with the microscope that this specimen has very small tubercles, strongly double-banded tibiae, and a fan tail.

I confirmed with the microscope that this nymph has small tubercles, single-banded tibiae, and a fan tail.

Pteronarcys nymphs live for two years before maturing. This small one is in its first year.

This is a really really really really tiny mayfly nymph. It has gills on abdominal segments 3-7 in the characteristic orientation for the Ephemerellidae family, and it has no fain tail as best I can tell, just uniform tail coverage with small black hairs of equal length. I think this one's too young to identify.

It has the segment 4 gill and abdominal segment 9 is longer than segment 8. I couldn't see abdominal tubercles, but they may not yet be developed in such an early instar.