Early action can help control flies in manure

Manure draws flies. It’s a universal truth.

But there are ways to limit the number of flies at feedlots and other livestock operations if the right steps are taken at the right times, says retired Agriculture Canada senior researcher Tim Lysyk.

As an entomologist, Lysyk has studied the ecology of flies that affect cattle. Houseflies and stable flies are the two types most annoying to cattle, and by extension, cattle people.

“Fly complaints can occur even in spite of your best efforts,” Lysyk told those at the Jan. 14 Manure Management Update event in Lethbridge.

While a certain amount of flies is inevitable, taking action in spring before peak fly season can help eliminate later season peaks, he said.

Houseflies and stable flies are the key species of interest.

Stable flies bite livestock and live on the resulting blood meals. They are mostly associated with cattle manure in both beef and dairy operations and can cause lower weight gains and feed conversion.

“We do get levels of feeding of the flies around here that certainly are equivalent to cause a fairly serious economic loss,” said Lysyk.

Houseflies can spread pathogens and are also annoying for the spotting they create through vomit and defecation. They will feed on any kind of protein that is available.

Lysyk said cultural methods are the cornerstone for integrated pest management. It starts with manure management, sanitation and moisture control.

“Without these, the other types of control options that are available really aren’t going to be quite as effective, either biological or chemical control.”

Flies can survive in manure that is 50 to 70 percent moisture, but if the manure is drier than that, fly survival is reduced and their natural enemies, including mites and beetles, can develop and help with control.

Reducing moisture through such things as leaking waterers and paying attention to drainage will help reduce flies, said Lysyk. Houseflies love silage, so covering silage and hay, where practical, is also useful.

“You don’t need to completely eliminate flies. You just need to keep them from being a bit of a problem,” he said.

Calf hutches on dairies can be a major harbour for flies just because of accumulated urine and manure. Lysyk said bedding of filtered cloth over absorbent material such as corncob bedding or sand has been shown to reduce that problem.

Spreading manure and incorporating it into soil does not necessarily eliminate flies, which can survive burial up to 33 centimetres deep. Lysyk suggested spreading manure in spring and fall when fly populations are lower.

Composting will eliminate flies, which can’t survive at temperatures above 50 C.

“In a nutshell, composting is probably one of the best ways to go,” he said.

The process kills the nutrients and bacteria that flies feed upon and reduces moisture at the same time.

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