The first year I arrived in Oklahoma, I was walking my dogs in the winter. I noticed hairworms on sidewalks, street gutters and lawns after heavy bouts of rain.
I have since visited 20 sites and found hairworms at 18. At each of these locations, I collected earthworms. In the lab, we dissected these earthworms and found that they contained cysts of these hairworms suggesting that females are laying eggs in/on the soil. Subsequent laboratory infections have found that we can infected earthworms with Gordius sp. eggs by placing them in soil.
Even more fascinating is that when we examine the eggs of this species, they have a double-membrane egg-a trait that has not been found in any species so far.
Hairworms found on sidewalk. December, 2016
Gordius sp. cyst in earthworm tissue.
Gordius sp. double-membrane egg.