12-3-11 Larvae-seeking Downy Woodpeckers
Robber flies have been covered in a previous posting, but their beak, or proboscis, deserves its own post, in my opinion. These predators perch and scan the sky for prey. When they see it they anticipate the prey’s direction and speed of flight and fly out and intercept it mid-air. Their objective is to paralyze the prey and liquify its insides so that the fly can drink it. The tip of the robber fly’s beak is covered with microscopic stiff bristles, designed to secure it within the wound it creates. Once this is achieved, a dagger-like shaft hidden inside the beak is used to stab its victim in the head or thorax and inject the paralyzing neurotoxic and digestive enzymes. The resulting fluid is sucked up by the fly’s beak, or proboscis.
If you want to get an idea of the number and variety of wasps, bees, beetles and bugs that reside in your area, go to the nearest goldenrod patch sit for a spell – this member of the Aster family is a magnet for insects. You’ll find many foliage- eating bugs and beetles, leaf-mining larvae, nectar and pollen feeders, and flower and seed-eaters. In addition, many predatory spiders (jumping and crab, especially) and insects (ambush bugs, ladybug beetles, flower bugs etc.) have discovered that goldenrod is a goldmine for them, as well. Researchers have found nearly 250 species of insects feeding on one species of goldenrod (Solidago canadensis). Pictured from left to right are a long-horned beetle (locust borer, Megacyllene robiniae – pollen eater), a fly (nectar feeder) and bee (nectar and pollen feeder).
Robber flies often perch on the leaves or stems of low plants waiting until suitable prey flies by, and then attack it in the air. They have long, strong, spiny legs for grabbing prey, and piercing-sucking mouthparts for consuming it. Robber flies prey on a variety of insects, including bees, beetles, bugs, dragonflies, grasshoppers, flies, leafhoppers and wasps. Once they capture an insect, they pierce it with their short, strong proboscis, or mouthpart, and inject their saliva into it. The saliva of robber flies contains enzymes that paralyze the insect and digest its insides, which the robber fly then drinks. The pictured robber fly is feasting on the innards of a stink bug it just captured.