Arizona Club-legged Hammertail
Efferia tagax
This record describes Efferia tagax (species). Recorded family: Asilidae. Recorded order: Diptera.
Identification and Appearance

Males are distinguished from other species of the albibarbis group by large size (over 25 mm), enlarged hind tibia, and mystax with mixed black and white hairs.
Classification
Habitat and Range
Geographic Range
Southwest USA
Additional species information
Species notes from the sources
Etymology: From Latin tagax , inclined to touch or (more likely in this case) steal. Arizona Club-legged Hammertail: https://www.robberfliesoftheworld.com/NA_CommonNames.php
About Flies: the wider group
Order-level background for Diptera, the group containing Efferia tagax. Species-specific details appear above.
Group overview
Diptera includes over 150,000 described species of flies, mosquitoes, and midges. Mosquitoes are the deadliest animal on Earth (CDC). Malaria alone causes ~249 million cases and over 608,000 deaths annually, mostly children under 5 (WHO). Vector-borne diseases account for over 17% of all infectious diseases, causing 700,000+ deaths per year.
Ecological role of the group
Despite their disease impact, flies are critical decomposers and pollinators. Hoverflies alone pollinate hundreds of crop and wildflower species. Flies are also the primary food source for many birds, bats, and fish. Forensic entomology relies heavily on fly species for crime scene analysis.
Economic and practical significance of the group
In the U.S., vector-borne disease cases tripled between 2004-2016, with over 640,000 cases reported in that period (CDC). Tickborne diseases doubled from 22,000 to 48,000 annual reports. Globally, mosquito-borne diseases cost billions in healthcare and lost productivity.
Recorded sources for this group: WHO, CDC, PNAS. Imported estimates may describe particular regions or reporting periods.
Photos of Arizona Club-legged Hammertail (5)
Photo credits: Contributed by John F. Carr; Additional contributions by Chris Cohen
Frequently Asked Questions About Arizona Club-legged Hammertail
What is Arizona Club-legged Hammertail?
Arizona Club-legged Hammertail (Efferia tagax) is a species in the family Asilidae, within the order Diptera.
How do you identify Arizona Club-legged Hammertail?
Males are distinguished from other species of the albibarbis group by large size (over 25 mm), enlarged hind tibia, and mystax with mixed black and white hairs.
Where is Arizona Club-legged Hammertail found?
Range: Southwest USA
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