Wasps interact with flies in various ways, and whether they kill them depends on the specific wasp species and its life cycle. The relationship between wasps and flies is not a simple one, encompassing both direct predation and a more intricate form of parasitism. Understanding these distinct behaviors reveals the complex ecological roles wasps play in natural systems.
Predatory Wasps and Their Fly Prey
Many wasp species are active hunters, capturing flies and other insects to feed themselves or, more commonly, their developing offspring. Social wasps, such as certain yellowjackets and hornets, use their jaws to subdue prey like flies. Their sting is typically reserved for defense of their nest. Solitary wasps, including mud daubers, potter wasps, and digger wasps, also exhibit predatory behaviors. They provision their nests with paralyzed or dead arthropods, including flies, as a food source for their larvae. Adult wasps themselves primarily feed on sugars from nectar or honeydew, but their larvae require a protein-rich diet. The captured flies provide this essential protein for the growing wasp larvae, ensuring their development. Ground wasps, for instance, are known to consume a range of insects, including flies, as part of their diet and to provision their young.
Parasitic Wasps and Fly Hosts
Distinct from predatory wasps, parasitic wasps, also known as parasitoids, utilize flies as living hosts for their offspring, ultimately leading to the host’s demise. These wasps are often very small, sometimes gnat-sized, and are largely unnoticed by humans.
Female parasitic wasps locate fly pupae, which are the non-feeding, immobile stage of the fly’s development, often found in manure or other organic matter. They then insert an egg into or onto the fly pupa.
Once the wasp egg hatches, the larval wasp feeds on the developing fly from within, consuming its tissues and fluids. This internal consumption prevents the fly from completing its metamorphosis and emerging as an adult. After the wasp larva completes its development, it emerges as an adult wasp from the now-dead fly pupal case, ready to continue the cycle.
Wasps as Natural Pest Controllers
The combined actions of predatory and parasitic wasps contribute significantly to the natural control of fly populations. Both types of wasps help regulate insect numbers, preventing them from reaching problematic levels that could damage crops or create nuisances.
Parasitic wasps are particularly valued in agricultural settings, where they are deployed in biological control programs to manage house flies and stable flies. These tiny wasps effectively reduce fly populations by targeting the immature stages of flies in breeding sites like manure accumulations. Their use can reduce the need for chemical insecticides, offering an environmentally conscious approach to pest management.
Commercial insectaries often provide various species of parasitic wasps for release in areas with high fly activity. Regular and timely releases of these beneficial insects can lead to a substantial decrease in fly numbers, making wasps valuable in maintaining ecological balance.