Myrmeleon mobilis

Hagen, 1888

Myrmeleon mobilis is a pit-making antlion in the Myrmeleontidae. The larva constructs conical pits in sandy substrate to trap small ground-dwelling arthropods, using a unique discontinuous gut physiology where solid waste is retained until adulthood. A 2005 microbiological study identified its bacterial associates as primarily Proteobacteria, including -like organisms in non-gut tissues and Enterobacteriaceae-like bacteria in the gut. The species is recorded from North America.

Pronunciation

How to pronounce Myrmeleon mobilis: //mɪrˈmiːliːən ˈmoʊbɪlɪs//

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Identification

Larvae identified by pit-making —constructing conical traps in fine sandy soil—and by morphological features including backward-only locomotion, long hooked hollow , and sand-dusted cryptic appearance. distinguished from by short clubbed (versus long slender antennae) and clumsy pattern. Differentiation from other Myrmeleon requires examination of specific morphological characters not detailed in available sources.

Habitat

Larval consists of fine, powdery dry soils or sawdust around rotten logs, typically in sheltered locations such as beneath rock overhangs, under bridges, at bases of trees, or in dry dirt floors of old barns and sheds. Colonies often occur where substrate remains perpetually dry. habitat includes tall grasses and vegetation, with individuals frequently observed near outdoor lights at night.

Distribution

Recorded from North America. Specific range details beyond continental-level occurrence are not documented in available sources.

Diet

Larvae are predatory, feeding on liquefied internal tissues of small ground-dwelling arthropods captured in pit traps, including ants and other insects. Prey is subdued with cocktails injected through hollow , enabling . feeding habits are largely unknown beyond consumption of soft-bodied insects and pollen.

Life Cycle

Complete with four stages: , larva, pupa, . Eggs laid in sandy soil. Larvae construct pit traps and feed until mature. occurs within silken cocoon spun underground, with sand grains incorporated into cocoon structure. Larval gut is discontinuous ( not connected to ), preventing elimination of solid waste until adulthood.

Behavior

Larvae exhibit unique backward-only locomotion, moving rapidly in reverse. Pit construction involves backward in a spiral while flicking sand with jaws and flattened to create symmetrical conical trap. Larva lies in wait at pit bottom, sensing prey vibrations and flicking additional sand to cause avalanches that carry victims downward. Captured prey is dragged beneath sand, injected with paralyzing , and consumed via ; dry carcass is subsequently catapulted from pit with violent head thrust. When disturbed, larvae bury themselves rapidly using backward shuffle. are cryptic, aligning body with substrate to become nearly invisible when at rest.

Ecological Role

Larvae function as sit-and-wait of small ground-dwelling arthropods, potentially influencing local and small insect . Microbiological study suggests bacterial may contribute to prey subduing toxins, though this role requires further investigation.

Human Relevance

Larvae are easily maintained in captivity using containers of fine sand with periodic prey provision, making them accessible study organisms for -prey interactions and pit construction . Commonly known by colloquial name "doodlebugs," possibly derived from random cursive trails larvae create when seeking new pit locations.

Similar Taxa

Scotoleon spp. antlions with similar delicate appearance; distinguished by more pronounced male abdominal claspers and lack of pit-making larval (larvae are free-living rather than pit-constructing).
Vella spp.Much larger antlion with wingspan of 100–120+ mm; restricted to southern third of United States and attracted to lights, versus smaller size and broader distribution of Myrmeleon.
Other Myrmeleontidae genera (non-Myrmeleon)In North America, only Myrmeleon larvae construct pit traps; all other have free-living larvae that bury themselves just below surface or hide under objects without building characteristic funnels.

More Details

Microbiota

Culture-independent 16S rRNA gene analysis identified bacterial dominated by Proteobacteria: -like α-Proteobacteria (75 , primarily in and body tissue) and Enterobacteriaceae-like γ-Proteobacteria (144 clones, predominantly in gut tissue). Community composition remained qualitatively similar across freshly caught, laboratory-fed, and laboratory-starved individuals, though libraries differed significantly between treatments.

Gut physiology

Discontinuous gut structure ( not connected to ) represents unusual preventing solid waste elimination until adulthood, with potential implications for microbial stability and nutrient processing.