FROM THE FARM REPORT: FLY SEASON IS COMING:PROACTIVE STEPS FOR PEST CONTROL

May in the Northeast can be an exciting time for farmers. We are out of the woods of winter, breaking ground, and getting seeds planted. But with warmer weather also comes a familiar challenge: flies.

Flies are most active in the Northeast from May through October and can have negative impacts on animal welfare and production. Flies are more than just a nuisance to cattle and humans. They irritate cattle, disrupt normal behaviors, and are a vector for disease transmission. In humans alone, flies are known to be responsible for the spread of over 65 diseases. Excessive fly populations can contribute to cows bunching to relieve fly pressure. This results in reduced lying times, which has a domino effect: decreased milk production and feed efficiency, increased lameness, and during the summer months, increased heat stress.

Flies are a universal issue for dairy farms because the warm, moist conditions common around livestock are perfect for fly breeding. It’s been estimated that flies contribute to millions of dollars of annual production loss in the dairy industry. That’s why fly management is crucial during the warmer months of the year.

The Fly Life Cycle

When developing a strategy for fly management, it’s first important to have some background on the life cycle of flies so that management can be targeted. Flies have 4 stages of life: egg, larva (maggot), pupa, and adult. Eggs will be laid in any moist decaying organic matter, like manure or wet rotten feed. The length of a fly’s life cycle depends on the species, but in general it can last up to 30 days. In that 30-day life, female flies will lay about 1,000 eggs that only take 10-12 hours to hatch. Once hatched, the eggs mature as maggots in warm moist environments for 4 to 5 days. Pupation then occurs for 3 to 5 days in drier areas before emerging as adults. Female flies begin laying eggs just 2 to 4 days after becoming adults. This rapid life cycle means that if not properly managed, fly population can explode in a matter of days. No single method will effectively control flies on its own. A successful program is one that includes a combination of routine sanitation and insecticide strategies.

Fly Control Strategies: Sanitation + Insecticides

Sanitation: Break the Reproductive Cycle

Insecticides will not be fully effective on fly control if there are poor sanitary conditions. Flies harbor inside and outside of barns in warm moist environments like manure, wet feed, or other decaying organic matter. To aid in controlling the fly population, it’s important to routinely remove these environments from the farm. Frequently removing manure from pens with an automated scraper, skid steer, or shovel, and scraping areas where manure might be building up will help remove fly breeding environments. Similarly, removing wet feed from feed bunks in a timely manner and spreading rotten feed on fields at least every 10 days will help break fly’s reproductive cycle. Overall barn cleanliness, including proper barnyard and bunk management, will make the environment less ideal for flies.

Insecticides: Targeting the Life Stages

In addition to routine sanitation, insecticides can be used to target specific life stages of flies. To target flies in the early stages of life, egg and larva, you can apply residual larvicides to places where flies lay their eggs. Larvicides can be very effective at reducing the adult population. To target adult flies, residual adulticides can be applied, and are often cheaper then larvicides. Adulticides may include sprays, baits, or on-animal treatments. Some places to consider applying insecticides include free-stall pens, manure storage and drainage area, feed bunk and mixing areas, and calf housing. The best time to apply insecticides is during the hottest part of the day, when flies are away in cooler areas. Most insecticides are most effective between 65°F and 90°F and can be broken down from sun UV rays. Follow directions for insecticide application exactly as the label reads.

Flies are a nuisance to us and our animals, but with proactive, consistent management strategies we can minimize their impact. Clean environments and targeted insecticide application breaks the fly life cycle and helps keep our cows more comfortable and productive all summer long.

— Emily Bourdeau

ebourdeau@whminer.com