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Insect pest management considerations

There are three main components of an integrated plan: adulticide, larvicide and an insect growth regulator.

By Wesley Lyons, DVM, Pipestone Veterinary Services
Summertime should mean school’s out, summer vacations, celebrating our nation’s independence, warmer temperatures and happy pigs. Unfortunately, with the warm weather we also see an increase in insect pests within our barns.

Depending on the region and barn ventilation setup, insect types can vary, but the common culprits are house flies, stable flies, dark-eyed fruit flies and mosquitoes. These pests may seem like an annoyance to employees, but imagine how the pigs feel living with them 24/7!

On top of the annoyance factor, we can’t forget research that implicates flies as potential routes of entry for both porcine reproductive and respiratory syndrome and porcine epidemic diarrhea virus.

When developing a pest management control program, it’s important to keep in mind that the flies we see are only about 15-20% of the true population. The fly life cycle means that, at a given time, there are four distinct life stages of a fly in the environment.

We focus on the adults, because that is what we see. To control the population, however, we must take a more holistic approach.

Diagram of life cycle of a fly.


The entire life cycle from egg-laying to sexually mature adult varies based on temperature and humidity, but can be as short as nine to 12 days in ideal conditions. With this knowledge, it’s easy to see why only killing adult flies won’t remedy a much larger problem.

Farmers have two major weapons against insect pests: controlling breeding areas around the farm and utilizing effective insecticides to target multiple life stages of the bugs.

Flies like to lay their eggs in dark, warm, humid environments. It’s easy to see why pig barns make great, year-round breeding environments.

When dealing with fly populations in a barn, farmers should think about both internal and external control. Internally, considerations should focus on pit levels, amount of crust build-up on the top of the pits, and other sources of standing water and feed wastage.

Externally, focus should be centered on standing water and compost piles.

The “integrated pest management plan” has recently been used to describe the comprehensive approach necessary to combat an insect pest problem.

There are three main components of an integrated plan: adulticide, larvicide and an insect growth regulator.

• Adulticide products come in a variety of formulations: meal bait, paint-on liquid, aerosol liquid and stick-on strips, to name a few. The aerosol products come in both animal-safe (can be applied when animals are present) and a long-acting (used when the barn is empty) formulations. Non-aerosol adulticide products typically have an attractant mechanism to draw flies to them, so do not place them at entry points to the barn. This will attract more flies and potentially make the problem worse.
• Larvicide products are generally a spray or fog-type product that are applied to the environment where flies lay their eggs. These products kill the larvae on contact.
• IGRs are arguably one of the most important aspects of an integrated plan. These products can be fed to the pigs, and the pigs then pass the product through their feces. There is no risk to the pig, and there is no absorption of the product, so there is no withdrawal time associated with many of these products. The IGR causes fly eggs laid in the feces to be unable to hatch, thus stopping the next generation of flies.

In summary, flies can be an annoyance and a health concern for growing pigs. We have several options for combatting fly populations in barns, but a systemic approach targeting multiple points in the life cycle is the best management technique.

Contact your veterinarian or our swine specialist team with questions about when and where to use these products.

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