Natural Enemies of Blackflies and Midges
Mesomermis
The genus Mesomermis includes a number of species that are important parasites of black flies. Welch (1962) described Mesomermis flumenalis as a parasite of Simulium vesnustum in Wisconsin. Morphologically similar mermithids have since been reported from many regions of North America though other aspects of their biology is often at variance, particularly host range information. M. flumenalis appears to be an complex of morphologically cryptic species which have yet to be clearly delineated. What follows is an illustration of some of the defining characteristics of Mesomermis flumenalis as seen in a parasite from the mountains of Southern California. This parasite or a similar one has been found in Simulium piperi, S. aureum, S. argus, S. virgatum, S. vittatum, and S. arcticum.
Mesomermis flumenalis complex
Infective Larva
The infective larva of M. flumenalis is characterized by a long tail. The tail is deciduous and is shed shortly after emerging from the host.
Adults Male
Males have paired, curved spicules with rounded tips.
Adult Female
Females have a short, pear-shaped vagina at a right angle to the body axis.
Mermithid Page
Last modified 19 December 1999
In distinquishing M. flumenalis from the newly described M. camdenensis Molloy (1979) pointed out the curved apical end of the preinfective larva tail in M. flumenalis. Compare the two similar organisms.