Scotoleon expansus
(Navás, 1913)
Scotoleon expansus is an antlion in the Myrmeleontidae, found in North and Middle America. are delicate, slender insects with lacy wings that superficially resemble damselflies but are distinguished by their short, clubbed . Males possess a notably longer tipped with bracket-like claspers. The larvae are predatory, burying themselves just below the soil surface to ambush prey rather than constructing pit traps.
Pronunciation
How to pronounce Scotoleon expansus: //ˌskɒtoʊˈliːən ɪkˈspænsəs//
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Identification
distinguished from damselflies (Odonata) by short, clubbed versus long, thread-like antennae. Distinguished from other antlion by male abdominal structure: Scotoleon males have longer with bracket-like claspers. Separated from Myrmeleon by larval —Scotoleon larvae do not construct pit traps, instead burying themselves just below the surface to ambush prey.
Habitat
frequent tall grasses, especially at dusk. Larvae occur in dry, sandy or powdery soils; found in sheltered situations such as beneath rock overhangs, under bridges, at the base of trees, and in the dirt floors of old barns and sheds. Colonies typically form in perpetually dry locations.
Distribution
Present in North America and Middle America. Records span the southwestern United States through Mexico.
Seasonality
most frequently observed at dusk. Attracted to lights at night. Activity patterns otherwise not well documented.
Diet
Larvae are predatory on ants and other small . have reduced mouthparts and do not feed, or feed only rarely.
Life Cycle
Complete with , larva, pupa, and stages. Larva spins a silken cocoon underground incorporating sand grains, within which occurs. Pupation takes place in the soil.
Behavior
Larvae bury themselves just below the soil surface and wait with jaws agape for prey to pass by—unlike Myrmeleon larvae, they do not construct pit traps. When prey contacts the larva, it injects through hollow to paralyze and externally digest the victim, then imbibes the liquefied tissues. are weak, clumsy fliers. When alighting on vegetation, adults align their bodies to flatten against the substrate, rendering them nearly invisible due to cryptic wing patterns.
Ecological Role
Larvae function as sit-and-wait of ground-dwelling insects, particularly ants. May contribute to soil aeration through larval burrowing activities.
Human Relevance
Larvae can be maintained in captivity in containers of fine sand with periodic introduction of prey items. occasionally attracted to porch lights. No significant economic impact documented.
Similar Taxa
- MyrmeleonLarvae construct conical pit traps in sand; Scotoleon larvae do not build pits but bury themselves just below the surface to ambush prey.
- Vella are substantially larger with wingspans of 100–120 mm or more; Scotoleon adults are smaller and more slender.
- Damselflies (Odonata: Zygoptera)Superficially similar in body form and wing appearance, but possess long, thread-like versus the short, clubbed antennae of antlions.
More Details
Historical taxonomy
Originally described as Brachynemurus expansus by Navás in 1913; later transferred to Scotoleon.