NORSK ENTOMOLOGISK TIDSSKRIFT - Norsk entomologisk forening

Ca9tura of Ca9nia bifrons (Newman) at (3verland 49
Fig. 2. Szterbekken, 20.111.65. The upper part, with a hole cut in the
ice 18.111 in order to collect nymphs.
the bottom with the foot and then catching the loosened nymphs
in a plankton net held straight down (cp. Langford 1964). At
Saterbekken were found 1 adult male and 1 femal. In an aquarium
1 male and 2 females were hatched.
Male nymphs of C. bifrons ready for emergence are easily
distinguished from the other Ca@zia species in our fauna in that
the wings are strongly reduced (fig. 3A). The last abdominal
segment of the male nymph is extended as shown in Fig. 3B. The
female nymph has normal wing pads (Fig. 3C). One male nymph,
from Saterbekken, ready for emergence, has been compared with
material from the Zoological Institution, Lund.
The skin of mature nymphs is easily removed and there- after
the determination of the male can be undertaken based on imago
characters. The length of male nymphs is 6-7 mm, of female
nymphs, 7-8 mm. Further, the male is much more slender than
the female. The colour of the nymphs is greyish brown, paler on
the underside. Some variation in colour occurs and it seems as
if the nymphs become a darker brown as they approach emergence.
Adults 2 males and 3 females. The colour of the body is darkbrown
to black; the legs are slightly lighter in colour. The male,
which is micropter, has a slender body about 5-6 mm long.
The last abdominal segments are shown in fig. 4. The females
which resemble the male in colour, have a broad lighter-coloured
band on the dorsal side of the abdomen. They were about 8 mm