Austrosimulium pestilens
FAMILY
Simuliidae
TAXONOMY
Austrosimulium pestilens Mackerras and Mackerras, 1948, Queensland, Australia.
OTHER COMMON NAMES
None known.
PHYSICAL CHARACTERISTICS
Adults are small, black, and humped-back, about 0.04 in (1 mm) in length. Eyes are holoptic (in contact with each other) in males and dichoptic (separated) in females. The larvae are 0.008–0.2 in (0.2–4.5 mm) in length, pale with irregular mottling. They have a pair of large cephalic fans on the head, a proleg (false leg) in the thorax, and another one at the tip of the abdomen, armed with a circlet of spines that anchors the larvae to submerged substrates. Pupae have a pair of breathing organs called spiracular gills that look like a collection of threads attached to the back of the head, which enable them to breathe while permanently submerged.
DISTRIBUTION
Queensland and northern New South Wales in Australia.
HABITAT
Larvae require oxygenated, running waters, and they live in both stony and weedy streams. Adults appear along the larval river or streams courses and the surrounding countryside.
BEHAVIOR
After mating, females look for a blood meal in open spaces, seldom entering buildings. Following the blood meal, females rest in trees and shrubs prior to oviposition.
FEEDING ECOLOGY AND DIET
Larvae filter drifting food with their fan-like mouthparts. Adult females require a blood meal before the first batch of eggs is laid. They are pool feeders, imbibing blood from a droplet created from cutting the skin.
REPRODUCTIVE BIOLOGY
Eggs are laid into fresh running water and sink to the bottom, where they can remain quiescent for at least five years on a damp stream bed, until they hatch with the next flood. Larvae construct well-formed silken cocoons when ready to pupate; the pupal stage lasts about two days. Adults usually emerge during daylight hours and float to the surface in a bubble of air. Males tend to emerge before females and form highly visible mating swarms associated with trees close to the water. Females enter these swarms, are captured, and mate, after which they seek a blood meal. Egglaying swarms are diffuse and occur throughout the daylight hours. Females fly low over the stream and dip their abdomens into the water surface. Adult flies may live up to three weeks.
CONSERVATION STATUS
Not threatened.
SIGNIFICANCE TO HUMANS
Considered a nuisance pest in Australia; females bite cattle, dingoes, goats, horses, humans, and marsupials such as kangaroos and wallabies.
