| Diogmites | |
|---|---|
 | |
| A male of Diogmites angustipennis from eastern New Mexico | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Diptera |
| Family: | Asilidae |
| Subfamily: | Dasypogoninae |
| Tribe: | Dasypogonini |
| Genus: | Diogmites Loew, 1866 |
| Type species | |
| Diogmites platypterus Loew, 1866 | |
| Species | |
Over 70, see text | |
Diogmites is a genus of mainly neotropical flies in the family Asilidae or robber flies.
Medium to large-sized robber flies (17–48 mm) with mostly minute body hair, thoracal bristles are mostly confined to a row on the mesonotum and two bristles on the scutellum. The mystax is of relatively modest size and is made up of comparatively few bristles, which do not or barely overlap the beak in side view. The antennae have a relatively slender third article that forms over half of the antennal length and carries a single, minute apical hair. Face narrower than the width of one eye. Abdomen slender and sometimes slightly constricted, its posterior end reaches the wing tips or extends past these. Wings are usually clear or only slightly tinted. Body coloration often predominantly straw-yellowish to orange-reddish, in some species darker brown to black. Eye coloration of live animals often includes iridescent green.
Legs comparatively long with prominent bristles, the length of the hind legs often roughly equals the length of the entire body. Forelegs about two-thirds as long as hind legs, with a short but distinctive curved spine at the anterior edge of each tibia. The claws of the hind legs are less than twice as long as the pulvilli. As is typical for Dasypogoninae, the harder cuticle of the prosternum is separated from the neck by an area of flexible cuticle that presumably allows for greater freedom of movement of the forelegs. This feature also occurs in some members of other asilid subfamilies. [1]
As with most asilids, known pupae of Diogmites species have prominent tooth- or hook-like anterior protrusions of the cuticle, which are technically referred to as antennal processes. In this genus there is one undivided pair of anterior antennal processes without any basal bristles, plus three posterior antennal processes [2] [3]
Adults of Diogmites species hunt as ambush predators, taking off from a resting position on the ground or on branches to intercept other flying insects, or to pounce on perching/crawling prey. After prey capture, these flies will feed in a characteristic posture that has earned this genus the common name of Hanging Thieves: they will hang from plant stems or leaves suspended by one or both front legs, with the other legs holding and manipulating the prey while feeding. Presumably the relatively long legs and reduced prosternum of the genus are part of adaptations to facilitate feeding during this suspended posture.
Hanging thieves should not be confused with predatory scorpionflies of the family Bittacidae which are commonly called Hangingflies and which actually capture flying prey in a suspended posture.
Many observations of the suspended feeding posture of Diogmites were caught on camera, for example Herschel Raney's webpage for Dasypogoninae includes images of D. angustipennis, D. platypterus and D. missouriensis feeding on a variety of insects. [4] Chris Thawley has an interesting video of a feeding adult manipulating a large prey wasp while in hanging posture. [5] Observations of the moment of prey capture are unfortunately not recorded yet in any literature or web resources. Some species can assume an unusual flight posture, with the first and last leg pairs raised high while the middle legs are extended downwards (personal observation of low-flying D. angustipennis males and females in central New Mexico). This might represent a peculiar type of hunting-related behavior more commonly referred to as orientation flights, or perhaps might serve purposes unrelated to hunting, such as a defensive posture to reduce odds of capture by dragonflies or other robberflies, or behavior intended to facilitate latching onto plant stems and leaves for landing.
Robert Lavigne's Predator-Prey Database for the family Asilidae [6] has 443 records of observations for at least 20 species of Diogmites feeding on a wide range of prey, including other asilids as well as dragonflies. Particular species can be selective in prey choice however, for example D. crudelis was observed to feed on Diptera or Hymenoptera in 89 of 93 cases. [7] Very little is known about larval biology, but D. misellus and D. neoternatus larvae were respectively observed and surmised to feed on scarabaeid grubs. [2] Larvae appear to live and pupate in soil, adults emerge after the pupae break through the soil surface to expose the anterior body. Whitney Cranshaw has captured emergence of an adult D. angustipennis in a series of remarkable photographs available at Zipcodezoo. [8] Norman Lavers' Illustrated Field Guide to The Robber Flies of Crowley's Ridge, Arkansas details egg-laying behavior of D. platypterus and includes a more detailed photo of a protruding pupal cuticle. [9]
Depending on the source, 73 to 77 species are currently recognized in Diogmites: [10] [11]
Although Diogmites is usually considered a member of the subfamily Dasypogoninae, combined analysis of morphological and molecular characters places Diogmites tristis in a clade corresponding to the subfamily Stenopogoninae instead, without however providing direct support for monophyly of this subfamily. [14]
The Asilidae are the robber fly family, also called assassin flies. They are powerfully built, bristly flies with a short, stout proboscis enclosing the sharp, sucking hypopharynx. The name "robber flies" reflects their expert predatory habits; they feed mainly or exclusively on other insects and, as a rule, they wait in ambush and catch their prey in flight.
Dasypogoninae is a subfamily of robber flies in the family Asilidae. There are more than 60 genera and 520 described species in Dasypogoninae.
Laphriinae is a subfamily of robber flies in the family Asilidae. There are more than 110 genera and 1,000 described species in Laphriinae. Larvae of the genus Hyperechia are known to grow inside the cells of Xylocopa bees, feeding on their larvae.
Prolepsis is an insect genus of mainly neotropical Diptera in the family Asilidae or robber flies.
Efferia is an insect genus of mainly neotropical and nearctic Diptera in the family Asilidae or robber flies. It is one of the most species-rich genera of Asilidae, with particularly high diversity in arid or semi-arid ecosystems of the New World.
Diogmites missouriensis is a species of robber flies in the family Asilidae.
Holcocephala is a genus of robber flies in the family Asilidae. There are at least 40 described species in Holcocephala.
Atomosia is a genus of robber flies in the family Asilidae. There are at least 60 described species in Atomosia.
Mydas is a genus of flies in the family Mydidae.
Lampria is a genus of robber flies in the family Asilidae. There are at least 20 described species in Lampria.
Mallophora bomboides, also known as the Florida bee killer, is a predaceous species of robber fly of the family Asilidae that feeds primarily on bumblebees. M. bomboides is a noteworthy instance of Batesian mimicry given its close resemblance to its prey, the bumblebee. These bees are typically found in the Eastern and Southern regions of the United States like South Carolina and Florida.
Diogmites texanus is a species of robber flies in the family Asilidae.
Plesiomma is a genus of robber flies in the family Asilidae. There are at least 20 described species in Plesiomma.
Dioctria rufipes, the common red-legged robberfly, is a species of robber fly in the subfamily Dasypogoninae of the family Asilidae.
Hyperechia is a genus of robber flies in the family Asilidae. They appear large, stout and with legs covered in bristles and appear like carpenter bees in the genus Xylocopa and the resemblance is considered as a case of aggressive mimicry, providing protection from predators. The larvae of the fly feed on the larvae of Xylocopa within their cavity nests in wood. They are mainly found in the African and Madagascan region with about 15 species and two species in Asia.