A Little Bit More
Robber flies are an impressive group of about 850 different species of true flies in North America (family Asilidae) that specializes in capturing flying insects such as bees, wasps, and dragonflies. It’s a bit difficult to imagine an insect attacking and subduing a wasp but this is exactly what some are able to do.
Typically, robber flies spend most of their time in open, sunny locations perched and ready to take off after a possible “meal” that crosses their field of view. They perch on branches, logs, stones, or the ground, and rush out to attack when suitable prey flies by. The robber fly uses its bristly legs to intercept its prey grasping it around the head or back. Then, using its needlelike mouthparts, the robber fly stabs its prey and injects saliva that contains nerve toxins and digestive enzymes. This quickly paralyzes its prey and liquefies its tissues; the robber fly then sucks out the prey's insides, much as spiders do.
Some robber flies closely resemble certain species of bumblebees. This may provide the flies with protection against potential predators, or it may enable the robber flies to more easily approach and attack the bees themselves – no one is sure. In any event, keep an eye out for these interesting, aerial predators the next time you’re out in an open area on a warm, summer’s day.
Activities
Science – Test your nature IQ
Objectives: Review of past EN units
Materials: On line access
This is an easy self-test that students can take — based on some of our recent Electronic Naturalist units. If you wish, feel free to have the students look back at the past 12 units to get their answers if they don’t already know them.
- What are the two basic oak groups in North America?
- Can you name one important product we get from trees?
- Once grown out, are feathers alive or dead structures?
- What do female wolf spiders sometimes carry on their backs?
- Can you name one major difference between butterflies and moths?
- Can you name a bird with webbed feet/toes that is not a duck?
- Can you name one major difference between lizards and salamanders?
- What’s it called when caterpillars “fly” through the air?
- What do scientists think Raccoons are doing when they “wash” their food ?
- Dragonfly nymphs have a special way of grabbing their prey. What do they use?
Key Concepts
Structures and Functions, Predator/Prey Relationships, Identification, Food Webs /Food Pyramids, Behavior and Regulation
Questions
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