(01/28/2006) Possible Explanation:
Horsehair worms lead Jerusalem crickets to water?
I read the account of the pond full of drowned ‘potato bugs’ and can offer a possible explanation — There is a group of ‘worms’ (Phylum Nematomorpha: Class Gorgonioidea – unless the systematics has been reworked since I was in school) that parasitize Jerusalem crickets, among other insects and crustaceans. The adults are free-living in freshwater, do not feed, and lay their eggs in the water. The hatched young parasitize an arthropod (and sometimes leeches). They go through multiple molts in the host’s body and do not emerge until they’re nearly adults. They emerge, according to my book, when the host is near water. More than once, I’ve seen a drowned Jerusalem cricket in a puddle of water with the very active horsehair worm that had just emerged. I recall my prof saying that the gordioid worms actually may be able to ‘force’ the Jerusalem crickets to enter pools deep enough to drown them (the Jerusalem cricket, that is), if there were no other water source available, but no one had figured out how that worked. The description of the pile of drowned Jerusalem crickets in the backyard pond your correspondent described is truly impressive — maybe they had a thriving population of horsehair worms in the garden! Your site is truly wonderful —

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