Robber Flies
Author: Ray Bowers

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Species: Pogonomyremex rugosus

Description:
Robber flies has an elongate tapering body that is about 25mm (1in) long. The head has short curved antennae, sucking mouthparts, large eyes with a hollow area between the eyes. The face has many hairs that give the fly a bearded appearance. The thorax has long stout legs, clear front wings, with reduced back wings that are knob-like in structure.

Geographic range:
Robber flies are found worldwide with nearly a thousand species in North America.

Habitat:
Robber flies are found in a variety of desert habitats, such as shrub lands, grasslands, and arroyos. They prefer open areas with plants on which they can perch.

Food Web:
Robber flies are predators feeding on any insects the can capture, such as wasps, dragonflies, grasshoppers, and other flies. They will sometimes attack insects larger than they are. The larval forms are also predators that usually feed on other insect larva.

Reproduction and Development:
Development is by complete metamorphosis. The eggs are laid in the soil or decaying plant matter. The maggot shaped larva hatch and grows. The next stage is a resting stage or pupa. During the resting stage the larva changes to the adult form.

Behavior:
Adult robber flies often have a perch that they prefer; when an insect flies by it will pursue the insect often catching it in flight. It then returns to its perch to feed with its sucking mouthparts. When robber flies are pursued they will fly a short distance, stop and observe their pursuer. The larval form crawls through the soil or dead plant material looking for other arthropodsto eat with their chewing mouthparts.

Ecosystem roles:
Robber flies feed on other insects and play a role in controlling insect populations. Their feeding is not discriminate and they will feed on any insect they can capture which may be another predatory insect. They in turn will be fed upon by any predatory that can catch them.

Taxonomy:

Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Atelocerata
Class: Hexapoda
Order: Diptera
Family: Asilidae
Genus: Promachus

References:
Borror, Donald J. and Richard E. White. 1970. A Field Guide to the Insects of America North of Mexico. Boston : Houghton Mifflin Co.

Borror, Donald J., Charles A. Triplehorn, and Norman F. Johnson. 1989. An Introduction to the Study of Insects. Philadelphia:W. B. Saunders Co.

Bland, Roger G and H. E. Jaques.1978. How to Know Insects. Dubuque, Iowa: Wm. C. Brown Co.

Related Terms: Hexapoda, Insects