I sometimes think of the insect order Megaloptera (fishflies, dobsonflies, and alderflies) as one of several “weird” orders. They aren’t nearly as common as many other insects, and they don’t look quite like anything else. Because of that I was happy to recently stumble upon this nearctic alderfly (Sialis sp., Sialidae).
Although adults like this may not feed, the larvae are predaceous. They crawl around on the bottom of rivers and streams hunting down other aquatic insects. They leave the water to pupate, but don’t form cocoons (Triplehorn and Johnson 2005). Adult alderflies are poor fliers, and they’re usually found close to the water they grew up in (Bouchard 2004). Since I found this individual along the River Raisin downstream of Blissfield Michigan, it probably lived in the river here as a larva. Interestingly, this section of river is generally regarded as having poor water quality, but alderfly larvae are considered moderately sensitive to poor water (Bouchard 2004).
Bouchard, R.W., Jr. 2004. Guide to aquatic macroinvertebrates of the Upper Midwest. Water Resources Center, University of Minnesota, St. Paul, MN. 208 pp.
Triplehorn, C.A. and N.F. Johnson. 2005. Borror and DeLong’s Introduction to the Study of Insects. Seventh Edition. Thomson Brooks/Cole, Belmont, CA.