This week has been tumultuous for Bug of the Week as we were deluged by questions about brown marmorated stink bugs. While the early indications suggested that this despicable invader had “no predators” in its new home, helpful viewers are proving this notion incorrect. Leslie writes that her Guinea hens gobbled hordes of brown marmorated stink bugs around her home.
Turning attention back to the realm of critters without backbones, Doug from Virginia sent a stunning photograph of a robber fly with a stink bug in a macabre embrace of death. Robber flies are one of the most fascinating groups of predators with more than 4,700 species on our planet. They consume a wide variety of prey, primarily other insects and spiders. Robber flies have large eyes, excellent vision, and they capture victims on the wing with strong forelegs. A powerful beak is inserted into the victim’s body once it is captured. Potent saliva laced with neurotoxins and digestive enzymes are pumped into the victim. Neurotoxins rapidly immobilize the prey while the digestive enzymes liquefy solid tissues that are easily sucked up through the beak and down the gullet of the fly. After a short time, the victim’s remains are discarded and the robber hunts again. Robber flies do not fear a tussle and often capture stinging insects such as bees more than half their size. Immature stages of robber flies are legless maggots. Their time is spent in the soil where they hunt and eat many different types of insects including pests such as white grubs. Several species of robber flies closely resemble stinging bees and wasps found in the same habitats. This ruse may provide protection from predators such as birds that learn to avoid stinging insects for dinner. By mimicking the appearance of bees and wasps, robber flies may also be able to dupe potential victims who mistakenly fail to identify them as foes rather than friends. For obvious reasons this clever form of deception is called aggressive mimicry.
Last week we met a different predator called the wheel bug that has learned to hunt and kill brown marmorated stink bugs. In addition to robber flies and wheel bugs, jumping spiders are deft hunters of stink bugs. In the field and on the screens of my windows at home, jumping spiders successfully stalk and capture much larger stink bugs. One true mistress of the art of capturing stink bugs is the European praying mantis, Mantis religiosa. Recently, my eagle-eyed colleague Holly the Bug Hunter spied a praying mantis in the process of dispatching a stink bug. By the time I arrived, the head of the bug was already removed and I just happened to photograph the stealthy green terror in the act of swallowing a stink bug leg. Yum! The European mantis was introduced to the United States from Europe in the 1890’s near Rochester, New York. This continental has adapted well to our land and is now found throughout much of the United States east of the Mississippi and northward into Canada. The name Mantis comes from the ancient Greeks who used mantis to describe a soothsayer or one that could see into the future. We can only hope that the mantis and her allies the assassin bugs, robber flies, and feathered fowl see a dark future for the nefarious stink bug.
We thank Doug, Leslie, and Holly for providing the inspiration for this episode. The fantastic robber fly world of Fritz Geller-Grimm; “An Introduction to the Study of Insects” by Borrer, De Long, and Tripplehorn; and “The Science of Entomology” by Romoser and Stoffolano were used as references for this episode.
For more information on robber flies and praying mantids, please visit the web sites below: