FAMILY
Asilidae
TAXONOMY
Asilus diadema Fabricius, 1781, Italy.
OTHER COMMON NAMES
None known.
PHYSICAL CHARACTERISTICS
Adults are large (about 0.6 in [15 mm]) and sexually dimorphic; males have black abdomen and blackish wings, and females have black abdomen with red markings and brownish wings and are usually larger. Eggs are white, long, oval, and are laid in groups of 1–6 in cocoons made with sand grains glued together and covered inside with a silky lining. Larvae are white to yellowish, elongate, cylindrical, and tapering at each end. Pupae have transverse rows of elongate spines or bristles arising dorsolaterally, and abdominal segment 9 has 1–4 pairs of strongly sclerotized terminal caudal hooks.
DISTRIBUTION
Central region of Mediterranean Europe.
HABITAT
Open, dry, and sandy areas such as steppes, partly eroded hill slopes, sandy hollows, weedy grass plots, dunes, dry meadows, pastures, and olive groves.
BEHAVIOR
Males continuously look for females. Females are more territorial, remaining longer at their foraging positions perched upwards on stems, or sometimes on the ground. They only fly if they see potential prey or if males disturb them. During periods of inactivity, they hang on stems of flowers and grasses or under leaves.
FEEDING ECOLOGY AND DIET
Larvae feed on larvae of scarab beetles (order Coleoptera, family Scarabeidae), and adults mostly on hymenopterans, including honey bees (Apis mellifera). With their long, thin legs, the strong spur at the apex of the foretibiae, and long proboscis, they are well adapted for subduing wasps and bees without being stung. After catching a prey in flight, they look for an appropriate perching site before sucking the prey's contents.
REPRODUCTIVE BIOLOGY
Mating is initiated after a short struggle, when the male grasps the female's ovipositor with his genital claspers. Final mating position is end-to-end. The female then flies with the male in copula looking for a suitable place to land. After mating, the female lays the eggs in clutches in the soil, protected inside sand cocoons. The four larval instars and the pupa live in the soil.
CONSERVATION STATUS
Not threatened.
SIGNIFICANCE TO HUMANS
None known.
