I saw a “hanging thief” this past week, and was dismayed that a honeybee was held in its clutches. Hanging Thieves are a type of Robber Fly (Asilidae Family). While interesting to watch, and fun to photograph, robber flies have never been a favorite of mine since it seems that any time I’ve seen their predatory behavior it is usually has a pollinator in their clutches. Eliminating wasps and bees seem counterintuitive to being a beneficial insect.
But, you have to go beyond what may be right there before your eyes and delve a little deeper into the making of a robber fly. They have huge appetites so they help maintain the natural balance among insect populations. While, they take parasitic wasps and flies, much of their prey consists of plant-feeding insects. Robber fly larvae live in the soil or in various other decaying organic materials that occur in their environment. Larvae are also predatory, feeding on eggs, larvae, or other soft-bodied insects. We must keep in mind that what goes on in the ground where we don’t see, might just be the more beneficial aspect of a given species.
The noticeable predation on bees has given the Mallophora species of Robber Flies the common name of “Bee Killers”. Not a testimony to my wanting them in the garden. But, the Bee Killers are ectoparasites on scarabaeid beetle grubs. Ahhh…they have won my heart. Kill those darn June Bugs in the making with my blessings!
Although robber flies are predators, they are sometimes prey for other animals, including spiders, birds, and larger predatory insects like assassin bugs, praying mantids, and even other robber flies. Moles and underground arthropod predators, such as centipedes and ground beetle larvae sometimes eat them.
So, they have their rung in the food chain and I will have to overlook the fact that when they are most visible, they might just behave in a manner that I don’t agree with. Ahh, nature. A delicate balancing act. You have to take the good with the bad…and are we humans really equipped to make the decision on which insect is more worthy than another? Aesthetics shouldn’t be a deciding factor. We need to look beyond the beauty of a butterfly or dragonfly and consider that a grub may just have an equally important role in the scheme of things. My advice is to not use personal aesthetic perceptions in making environmental decisions. After all, who wouldn’t choose a beautiful and cute lion cub over some pasty looking human. Food for thought!
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