Reesimermis nielseni

This nematode grows to an average length of 15 mm (0.6 in); It tends to be longer in larger hosts and shorter when there are several parasites in one host.^[2]

Reesimermis nielseni is a parasite of the larvae of mosquitoes. It is known to infect 22 different species of mosquito in the wild and another 33 species in the laboratory.^[2]

On emerging from their host larvae, these nematodes fall to the bottom of the water body. They become sexually mature in about sixty days and females lay a total of around 2,500 eggs over a period of eighteen days or so. The eggs hatch after four weeks and each preparasitic larva searches for a suitable host; it will die if it does not find one within seventy-two hours. It bores a hole through the cuticle of the host mosquito larva with a stylet, and develops in its body cavity. When ready to leave the mosquito larva, it bores a larger hole through which it emerges. The mosquito larva does not survive because its body fluids leak out through the hole.^[2][3]