Tuesday, May 25, 2010
Check This Out.
This guy, about 2 inches long, is a fishfly. At first, we thought it was a dobsonfly, but I couldn't figure out why this dobsonfly had feathered antennae and none of the pictures I found did... nor did the two other, similar insects we found today. The answer, which Chris found, is hidden in the text (and not shown in the illustration) of the Peterson Insect guide... dobsonflies and fishflies are so similar they get the same entry, and are distinguished by this sentence: "Fishflies are smaller... and may have serrate or pectinate antennae..." So this, I guess, is a fishfly.
Fishfly or dobsonfly, I've never seen one as an adult before. (That is to say, the adult form of the insect, not that I wasn't an adult.) Like dragonflies, these fellows spend the majority of their lives underwater. Their larval form, often called a hellgrammite, I have seen, although never here. They are sort of creepy -- large, legged worms that prey upon smaller critters, including minnows. After spending one or more years as the familiar (to me) macroinvertebrates, they pupate on land. When they emerge as adults, they live for only a few days -- they can mate but they cannot eat. And so, the perfectly timed emergence of the megaloptera must be occurring... right. about. now.
This is good news for the local watershed... adult fishflies and dobsonflies do not stray far from their home body of water, and the hellgrammites are quite sensitive to pollutants. For them to live here means our water quality is good -- and even if I've never caught a larva here, the presence of the adults tells me they must be here.