Many robber flies tend to be dark (gray or black) and moderately sized with long, tapering abdomens. These flies perch on rocks with their wings lying flat over their backs. When disturbed they will often buzz loudly as they fly to another perch a short distance away. These flies tend to be sit-and-wait predators, dashing out from their perch to catch small insects and landing to feed. They also tend to stay close to the ground. The short beak can inflict a painful stab.
This is the large robber fly in the Display Case in the Visitor Center.
Note that the beak in the head-on view blends with the mounting pin which
holds the insect up and this makes the beak look longer than it really is.
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