Finding alternative methods to naturally control flies 

Fly control is an issue for all farmers, but organic dairy producers who are unable to use most existing chemical-based control methods are in a particularly difficult position. Researchers at the University of Guelph’s Alfred and Kemptville campuses are developing alternative, natural methods for pest control to help the organic sector and provide more options for conventional producers.  

Dr. Simon Lachance, from the Centre for Organic Dairy Research at the University of Guelph, Alfred Campus, is leading a three-year research project to develop and test alternative fly control methods – using both competing insects, essential oils and other natural products – in the hopes of repelling and controlling fly populations on organic farms.  

“It’s well known that flies can result in significant losses in production,” says Lachance. “Controlling these flies in pastures and inside buildings is a useful way to promote the health and welfare of animals.”

In pastures, the horn fly, which feeds on the back of the animals, and the face fly,  which can cause diseases such as pink eye, are the most problematic.  Inside buildings, it’s the house fly and the biting-stable fly that cause the most difficulties.

Flies not only carry disease, but distract cattle from grazing. That means less milk production and weight gain, resulting in an economic loss for farmers.  

In lab experiments, Lachance has been testing how well vapours from essential oils repel flies.  Essential oils are volatile liquid substances extracted from plants that contain ketone and ester alcohol.  He’s also using different essential oils and observing their impact on fly mortality rates.  So far, citrus oils and oils extracted from coniferous trees have proved most effective.

As part of an organic fly-control program, Lachance is also looking at the use of competitive insects, such as tiny parasite wasps, to control fly pupae. In most environments, female flies will lay 300-500 eggs at a time in manure, which hatch into maggots after two to three days.  The maggots will then transform into pupae, which is the stage targeted by the wasps as they lay their eggs inside the pupae.  The introduction of wasps into dairy barns may allow for control of the fly population, with no negative impact on the livestock.    

Lachance plans to start two years of field trials in the spring to determine the success of his lab findings.  He is also hoping to test the effectiveness of essential oils as an antiseptic, allowing for the possible management of mastitis-causing micro-organisms.  He suspects these essential oils could be used on surfaces and on the animals themselves, and is currently examining the effectiveness of applying them to straw bedding.

This research will provide producers with more tools for pest management and can be easily integrated into any existing system, whether organic or conventional.  

This research is sponsored by Dairy Farmers of Ontario, the Ontario Ministry of Agriculture, Food and Rural Affairs, Organic Meadow Co-operative and Harmony Organic Dairy Products Inc.