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Bulletin Wisconsin Natural History Society [Vol. 13, No. 2 
B. Larvae pale, slender, semi-aquatic or terrestrial; last segment slender, 
tapering. No ventral chitinous plates. Dorsal chitinous plates 
present on some segments. Bristles varied Psychoda 
a. Thoracic annuli with chitinous plates 
b. Chitinous plates present on all annuli of thorax and abdomen 
(2 each on three thoracic and first abd. segments, 3 each on 
abd. segments two to seven) ; eyes present, black ; length 5 mm. 
cinerea Banks 
bb. Chitinous plates absent from abdominal segment one (rarely 
one plate on posterior annulus) ; (eyes not stated, absent 
from figure) ; length 6-7 mm domestica Haseman 
aa. Thoracic annuli without chitinous plates, these confined to pos- 
terior segments of abdomen. 
b. Annular chitinous plates on six to seven of abdomen 
c. All segments with regular arrangement of paired setae; 
eyes absent (supposition), length 11 mm.. 
nocturnala Haseman 
cc. Segments without definite arrangement of longer setae; 
eyes absent; length 5 mm schizura Kircoid 
bb. Annular chitinous plates on five to seven of abdomen 
c. Segments with groups of dorsal, lateral and ventral setae; 
three annular plates each on five to seven; eyes present, 
brown; length 9 mm.; larva semiaquatic, at surface 
albimaculata Welch 
d. Segments without regular setae; annular plates three 
each to segments five to seven; eyes present, minute 
and black; length 8 mm.; larva aquatic, submerged. 
floridica Haseman 
The number of known (six) life histories is very disproportion- 
ate to the number of known species (over thirty of Psychoda, 
about fifty for the family). The chief trouble of breeding lies 
in the minuteness of the adult and the resultant difficulties in 
arranging suitable habitats for breeding purposes. 
The larva lives in the thin film of water covering the decay- 
ing vegetable cultures. They are active at all times, moving 
about and feeding apparently without rest. Though found in 
the surface film of water the larvae are not aquatic in the true 
sense of the term. In the live larva the two tracheal trunks can 
be seen to extend through the entire body, each side of the mid- 
line, each dividing anteriorly in the prothorax into three branches, 
the largest of which passes to the respiratory tubercle of the pro- 
thorax, the other two passing to the brain and mouth-parts, 
respectively. Posteriorly, the probability is that the two trunks 
