These insects naturally prey on all kinds of pests we don’t like, from mealyworms in Thailand to horseflies in North America. The way they work is, well, pretty gross: They lay their eggs directly into the pest, and when the wasp eggs hatch, they eat their way out, killing their pest-home. It’s gruesome! Nature red in tooth and claw!
Farmers can buy wasps to use as pest control, though often they’re done as a last-ditch option rather than for prevention since they can be kind of expensive; certainly more than spray-on pesticides. (On the other hand, you don’t forfeit your organic certification if you use wasps as pest control.) The specific ways wasps are used isn’t all that well understood, which a new paper, published in the Journal of Integrated Pest Management, points out.
Horseflies are a perfect example. Horseflies are well-known to humans for their aggressive, blood-sucking bite; they can take a chunk of flesh out with their powerful jaws. But for animals, especially horses, they can be much more dangerous. They can transmit equine infectious anemia, sometimes known as swamp fever, which can result in lethargy, weight loss, and even death. Parasitic wasps are a great candidate for pest control against horseflies, but not all that much is known about how they operate and what they prefer.
Turns out, individual species prefer specific livestock dung for breeding, which is important for figuring out which variety of wasp is best to provide long-lasting pest prevention. You have to make sure that the wasp wants to stick around your farm and attack your pests, and that means giving the wasp a nice home. And the wasp wants specific kinds of dung. No judgments! Some of us still live in New York City. We all have our weird housing preferences.
Anyway, the study determined a specific species that prefers horse dung, and another that prefers cow dung, which could easily increase the efficiency of parasitic wasps as pest control agents. It’s gross, scary, and weird, but this is what’s involved in figuring out how best to get rid of pests without dangerous synthetic chemical pesticides.