Hammertails
Efferia
Classification
Pronunciation
How to pronounce Efferia: /ɛˈfɛr.i.a/
These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.
Images
Summary
Efferia is a diverse genus of robber flies in the Asilidae family, notable for their predatory behavior in arid ecosystems, with pronounced sexual dimorphism in body and genitalia.
Physical Characteristics
Small to large-sized robber flies (10–40 mm) with distinctly different posterior abdomen shapes in males and females. Females possess a short or long, hairless ovipositor; males have a 'helicopter tail' with glossy black claspers. Abdominal coloration is generally greyish to brownish in females, whereas males display contrasting silvery and/or black segments. Wings vary from transparent brown to dark black, with a venation that includes a recurrent vein on R1 and a narrow cell r4.
Identification Tips
Males can be identified by their larger genital structures compared to abdominal segments, and the unique pulsing buzz they emit while flying. Spotting often involves listening for their distinctive flight sound first.
Habitat
Arid or semi-arid ecosystems, especially in deserts and grasslands of the New World.
Distribution
Primarily in the southwestern United States, with some species being more widespread in western regions and two species being across broader areas. Nerax mostly found in the southeast.
Diet
Ambush predators that feed primarily on a wide variety of insect orders including Diptera, Homoptera, Hymenoptera, Heteroptera, Coleoptera, Lepidoptera, and Orthoptera. Cannibalism is common.
Life Cycle
Adults intercept flying insects in mid-air, often from a resting position. They are known to perch close to the ground and can be relatively immobile until disturbed.
Reproduction
Females lay eggs in suitable habitats, but specific egg-laying behaviors are not detailed in the sources.
Predators
Other robber flies, as Efferia species can be cannibalistic.
Ecosystem Role
As predators, they play an important role in controlling insect populations within their ecosystem.
Collecting Methods
- Netting during flight
- Hand collecting from resting sites
Preservation Methods
- Ethanol
- Drying in a suitable preservative
Evolution
Phylogenetic analysis suggests Efferia is monophyletic and closely related to the subfamily Asilinae, specifically related to Proctacanthus philadelphicus.
Similar Taxa
Misconceptions
Some may confuse Efferia with other similar-sized flies or misidentify them due to their varied coloration and size ranges.
Tags
- Efferia
- robber flies
- diptera
- Asilidae