Entomophthora  -  The Fly Killer

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Death of the Flies (more images below)

In the warm days of spring flies by the dozens will often buzz around the windows of your home. This is especially true in some of the older homes and particularly farm houses. The flies congregate frantically around windows trying to escape to the outside. Occasionally they beeline for a lamp and whiz around madly in circles bumping against the shade. These are cluster flies and parasitize earthworms. They overwinter inside the walls of houses and emerge on warm, humid days to lay their eggs on the unsuspecting worms which are themselves emerging from their winter sleep.  If they emerge on the inside of the wall instead of the outside then you have a problem!

House flies behave differently and are also a real nuisance because they fly around the house getting on to food and the way they feed is not good. They squirt some enzymes in fluid from their proboscis onto the food surface then suck it back up. At the same time they spread their fair share of bacteria around from their feet, proboscis and who know’s where else. Cluster flies inside the home show no interest in food or people.

Entomophthora is the genus name for a group of fungi that attack and kill house flies, cluster flies root maggot fly, and many other insects with two wings ( = Diptera in entobabble). The word Entomophthora means insect destroyer.

Occasionally you will find a fly stuck to the window by its proboscis with a white halo encircling the body.  The fly has been killed by Entomophthora.   The halo is produced by large numbers of spores that have been shot off from the body of the victim. If you look carefully you will see that the fly appears striped. The fungus grows inside the body and proliferates to the point where it pushes the abdominal segments apart and bursts through to give the fly a banded appearance (check below for the micrograph of a section through one of these same flies).

Right hand photo:   Adult of the root maggot fly (Delia) that has been attacked and killed by Entomophthora.  The body is filled with the fungus growth that has burst out between the segments and through the bottom of the abdominal wall.  Just before death the flies fly to someplace high up and cement themselves by their proboscis.  This fly is attached to conifer needles.  I  once collected a hundred flies in twenty minutes that had been killed by Entomophthora and  attached themsleves to grass flowers around my property.

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(All images from MycoAlbum CD  by GLB)

Micrograph Left: Section through one of the infected flies showing the terminal helmet-shaped spores arising from elongate, multinucelate sporophores.   Diagram Right: Note at maturity ALL the nuclei and asociated protoplasm migrates into the single terminal spore (sporangium, conidium, whatever?) and sporophore (sporangiophore?) is now empty of content.

(Original material collected, fixed, embedded in wax, sectioned, and stained by ME.  Couldn't do it now!!!)