FNZ 20 - Bibionidae (Insecta: Diptera) - Biology
Harrison, RA 1990. Bibionidae (Insecta: Diptera). Fauna of New Zealand 20, 28 pages.
(
ISSN 0111-5383 (print),
;
no.
20.
ISBN 0-477-02595-1 (print),
).
Published 13 Nov 1990
ZooBank: http://zoobank.org/References/B52BAEA5-8E92-48C2-88FD-C08826C7DCAA
Biology
Adult habitats and food
Most of this information comes from my own collecting notes and from the labels of specimens examined. Adults are associated with a wide range of plant species (Table 1, p. 19) and feed on flowers, probably consuming the nectar and other exudations. Flowers of some plants are very attractive to bibionids, and during the months of peak activity (November to February) are visited by adults in swarm-like numbers. Two such flowers are those of citrus and cordyline, and there are probably others from the list of plants in Table 1 which are just as attractive.
Pre-adult habitats and food
An account of the habitat of D. nigrostigma is given by Hudson (1892). He records that larvae frequently inhabit the woody powder often found under rotting logs, that they are gregarious, and that larvae live for up to 8 months, pupating in spring. Harris (1983) records that larval D. nigrostigma are abundant in forest margins under fallen leaves of broad-leaved trees, both exotic and native. He cultured D. nigrostigma and D. segnis in boxes with soil and leaves, and adults emerged. Textbooks (Tillyard 1926, Colless & McAlpine 1970) generalise that Australasian bibionid larvae inhabit soil or decomposing vegetation, some feeding on plant roots, but probably on dead tissue. Larvae of New Zealand species probably all occur in decaying vegetation at soil level. None have been found in living plant tissue.
Generally, world wide, bibionid larvae are recorded as occupying the range of habitats described above. Pupae appear to be always found in the soil.
Economic Importance
The economic importance of bibionids is unclear, but larvae are not generally regarded as likely to be of great significance to crops or other plants. Hardy (1961) noted that larvae have been recorded as damaging vegetable or cereal crops.
Adults which feed on nectar may play a part in pollination.
Seasonality
Adults have been collected from July through to April, with peak populations in the summer months, generally November to February.