The most significant insect pests of mushroom cultivation belong to the Order Diptera
(two-winged flies)
comprising three families Sciaridae (sciarids), Phoridae (phorids) and Cecidomyiidae (cecids).
Adult sciarids are small (c.3-4 mm), delicate, two-winged flies which are dark grey/
black with large compound eyes and long, threadlike antennae. Females are generally larger than males
and their abdomens are often distended with eggs. Adults do not fly readily but move rapidly across
the growing surface in brief jumping flights. They may also be found "roosting" in tight spaces
and on the walls of production houses.
Adult flies may be present on mushroom
production sites throughout the year but are most numerous during May - November. On average, a mated
female can lay 150-170 white, oval eggs singly, or in groups within the growing substrate. Depending
on temperature, these eggs will hatch within three to four days to produce larvae.
Sciarid larvae are white, elongate, legless maggots with a distinctive black shiny
head. At this stage the larvae feed on developing mycelium and uncontrolled will burrow into pinheads
and small buttons forming a sponge-like mass. Mature larvae are approximately 8.0 mm in length and can
remove mycelial attachments at the base of the stalk and in severe infestations may enter stalks and
caps.
It has been demonstrated that a mean of one sciarid larva in 125g of
casing causes 0.5% loss in total yield. As the cost for recommended sciarid control measures also accounts
for 0.5% of the value of the crop, this represents an economic threshold for this pest.
Larval development is temperature-dependent but after approximately 12-15 days, the larvae transform
into pupae. This is an inactive stage, which does not feed. Adult emergence normally occurs following
5-7 days pupation. (
Sciaridae Life-Cycle)
