Sep 8, 2011 – Why The Fly?

QUESTION:

What attracts flies to the lawn? What is the best way to get rid of them?

ANSWER:

This will depend a great deal on what kinds of flies these are. There are a few kinds whose larvae feed on decaying thatch, such as March flies and Crane flies, and if there is a buildup of thatch on the lawn it will draw the adult flies to deposit their eggs there. The crane fly is really only a problem in the upper Northwest states of WA and OR where the European Crane Fly exists and causes damage to turf. It may feed primarily on thatch, but it also manages to munch on turf roots and stems. March flies, which are called "love bugs" when their populations explode along eastern states, are another whose larvae normally stick to decaying plant materials such as the thatch, but also will feed on roots of turf. The march flies are very slow fliers, fairly small flies, and usually black in the western states. The infamous love bugs of the east are black with a bright red-orange thorax.

Control of march flies may have to involve an insecticide application, but can also benefit from de-thatching of the turf. The buildup of thatch is caused primarily by an accumulation of the cut stems of the turf, as the blades are so easily decomposed that some universities even recommend leaving cut blades on the lawn to recycle the moisture in them. Stems, however, do not decompose as easily, so proper mowing intervals can reduce the thatch buildup. Thatch forms a thick layer over the soil that encourages many kinds of insects as well as fungus problems, so removing thatch benefits the lawn overall.

Other kinds of flies may simply be attracted to other things on the lawn, such as pet urine or feces which attracts blow flies and other filth flies. The use of organic fertilizers which could contain manure will also be attractive to these flies, and the only way to resolve this would be to change the kind of fertilizer if the flies are intolerable, and to get pets to poop somewhere else or to remove the waste materials immediately. Some kinds of fungi also become attractive to flies, such as the "stink horn" fungi that may startle a homeowner who finds them growing in their lawn. These odd fungi have a rather.......well......phallic appearance, and some of the Latin names for them even refer to this appearance. Their manner of spore dispersal is to produce a slime that smells remarkably like rotting feces, and this draws blow flies that land on the slime and then carry it to other places. Removal of the fungi is the control measure here.

Gather some of the flies and have them identified, and this will then give you hints on their biology and kinds of food resources. Control will normally be more cultural than chemical for flies.

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