Just another Dobsonfly Photo…
I live in Central PA near the Conodoguinet creek and the Susquehanna river. I am glad to see the Dobsonfly in our area, as they are proof positive that these bodies of water are doing well. I have been seeing a few each summer. Just one question, how far do these insects travel from water after emerging? We live 2-3 miles from both of these bodies of water. Why would they travel so far? I do have a small drainage stream behind my house. It is only a few inches deep most of the year and has been known to almost completely dry up in long summer droughts. I have seen no signs of aquatic life back there but the drainage field is only at the bottom of my road and I am sure there are things living in there. Could hellgrammites be living in either this small stream or the drainage field? I don’t imagine the water quality is too good in either case due to the fact that they are fed completely by runoff from the local streets and yards. I would think that the levels of miscellaneous chemicals and petroleum products are quite high. I have always been told that hellgrammites need clean flowing water to thrive. Any ideas?
Often the old texts have obsolete information when it comes to names and classification, but they often contain valuable observations. Here is something written by Comstock: “Corydalus.–The only member of this genus in our fauna is Corydalus cornutus. This is a magnificent insect, which has a wing-expanse of from 100 to 130 mm. …[The male] has remarkable long mandibles. The female resembles the male, except that the mandibles are comparatively short. The larva are called dobsons or hellgrammites by anglers and are used by them for bait, expecially for bass. … These larvae live under stones in the beds of streams. They are most abundant where the water flows swiftest. They feed upon the naiads of stone-flies and May-flies and on other insects. … When about two years and eleven months old, the larva leaves the water and makes a cell under a stone or some other object on or near the bank of the stream. This occurs during the early part of the summer; here the larva changes to a pupa In about a month after the larva leaves the water, the adult insect appears. The eggs are then soon laid; these are attached to stones or other objects overhanging the water. They are laid in blotch-like masses, which are chalky white in color and measure from 12mm. to nearly 25 mm. in diameter. A single mass contains from two thousand to three thousand eggs. When the larvae hatch they at once find their way into the water, where they remain until full-grown.” So, if you live 2-3 miles from the body of water, my assumption is that they are carried by the wind since they are not particularly strong fliers.