Cycle of the Small
The tiny blue disc shaped eggs measure c. 0.45 mm in
diameter and are laid singly among the flower buds of
Kidney Vetch from about late May to the end of June and hatch in c. 10 days. There may be
two or three on
each flowerhead, laid by different females.
deposited among the woolly
calyxes of Kidney Vetch.
© DHardiman 2001
The fully grown larva is short and stout measuring up to 10 mm in length and
tapering towards the extremities.
The body is pale ochreous and sometimes tinged with green. It has
a brown mediodorsal line and a white,
sometimes pink tinged, line on each side below the level of the
spiracles. The small head is shiny black and
can be retracted into the body. The body is covered with
Blue full-grown larva well
camouflaged on Kidney Vetch.
The young larva bores into the flower to feed on the developing
seeds, it will also eats other larvae of
its own species encountered. By mid-July the adult lives openly on the
seedhead and is fully grown
by mid - late July. At this stage it enters diapause,
and pupates the following spring .
The overwintering larva emerges about mid-April to early June and
pupates without further feeding.
The pupa is attached to a silk pad produced by the larva on a moss
stem, blade of grass, leaf or in a soil crevice.
It is suspended from the pad by its cremasteral hooks and supported
by a silk girdle. Pupation lasts from 6-18
days, depending on the temperature.
The adult emerges, after the overwintering phase, in May to early