Asilidae

Common brown robberfly with prey

Asilidae 5 by kadavoor

File:Laphria flava - 2013-07-05.webm

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Choerades fimbriata01

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Robber Fly with prey (Holcocephala fusca) by Thomas Shahan

Asilidae, commonly known as robber flies or assassin flies, are a large and diverse family of predatory flies known for their aggressive behavior. With over 7,500 described species distributed worldwide, Asilidae represent one of the most prolific families within the order Diptera. These insects are highly adaptable, inhabiting a wide range of environments from deserts to forests, and are recognized by their stout, spiny legs, a dense moustache of bristles on the face (mystax), and a powerful, piercing proboscis.

Description

Robber flies are characterized by their robust build, ranging in size from 5 to 50 mm. They possess a distinctive appearance with a long, tapered abdomen, a hunched back, and a head that is typically wider than the thorax. The mystax, a key identifying feature, serves to protect the head and face when attacking prey. Their compound eyes are large and prominent, providing them with excellent vision to spot potential prey from a distance.

Behavior and Ecology

Asilidae are solitary predators that ambush their prey in flight. Their diet is diverse, including other insects such as flies, beetles, butterflies and moths, and even smaller species of dragonflies. They employ their strong legs to grasp prey while delivering a lethal stab with their proboscis, injecting saliva that contains neurotoxic and proteolytic enzymes to immobilize and digest the internal organs of their victim.

The life cycle of robber flies includes egg, larva, pupa, and adult stages. Females lay eggs in soil, on plants, or in decaying organic matter. The larval stage, which can last up to several years depending on the species, is also predatory, feeding on soil-dwelling insects and larvae.

Taxonomy and Classification

The family Asilidae is divided into several subfamilies, such as Asilinae, Laphriinae, and Leptogastrinae, among others. The classification is primarily based on morphological characteristics of the adults and larvae, as well as genetic data.

Conservation

While many species of robber flies are common and not currently at risk, habitat destruction and pollution pose threats to some specialized species. Conservation efforts are important to preserve their habitats and the biodiversity they contribute to.

In Culture

Due to their predatory nature and formidable appearance, robber flies have captured human interest and are often subjects in macro photography and entomological studies. However, they are sometimes mistaken for aggressive towards humans, which is not the case; robber flies rarely bite humans unless handled or threatened.