330 THE BLOWFLIES oF NortH AMERICA 
Second instar: Segmental spinose bands wider than in 
previous instar and essentially as in following instar. Anterior 
spiracles each with 8 (8-10) rounded orifices; posterior spiracles 
each with two well-defined slitlike apertures. Cephaloskeleton 
(pl. 45, B) with labial sclerite more strongly sclerotized than 
in previous instar, still strongly arched, the hypostomal sclerite 
and pharyngeal sclerite more strongly sclerotized, the latter with 
dorsal and ventral cornua not so obviously separated as in the 
previous instar. 
Third instar: Cephalic segments (pl. 45, C) with distinct, 
branching oral grooves radiating from oral opening. Segments 
2 to 9 with complete anterior spinose bands, segments 10 to 12 
bare anterodorsally, segments 2 to 5 bare posteriorly; segments 
9 to 11 with complete posterior spinose bands, segment 12 bare 
dorsally. Spines minute, single-pointed, deeply pigmented. In- 
ner tubercles on dorsal surface of posterior depression separated 
by nearly two times the diameter of one spiracular plate, median 
and outer tubercles closest together, tubercles on ventral mar- 
gin nearly equidistant. Anterior spiracles as in the preceding 
instar; posterior spiracles (pl. 45, D) more heavily sclerotized, 
the three slit-like apertures, peritreme and ‘‘button’’ more dis- 
tinetly outlined. Anal protuberance surrounded by a wide band 
of spines which is narrowest laterally and widest. dorsally. 
Cephaloskeleton ( pl. 45, C) with labial sclerite not so strongly 
arched as in previous instar but basal portion wide. 
According to Bishopp (1915) the larvae are ravenous and 
mature within three to five days; puparia are formed in from 
five to 39 days after the larvae emerge from the eggs. They 
are killed by low temperatures according to Roberts (1930), 
who stated that probably only those which have finished feeding 
and are ready to migrate prepare for hibernation at the approach 
of cold weather. 
Puparwum. With the habitus of the puparium of Calliphora 
vicina and the major external characters of the mature larva. 
Bishopp (1915) stated that the pupal stage lasts for from 6 to 
58 days and that the complete developmental period is from 19 
to 99 days. Roberts (1930) found that puparia were formed from 
one and one-half to two inches below the surface of the soil. 
Adult. The preoviposition period lasts from 7 to 20 days 
according to Bishopp (zbid.). Overwintering apparently occurs 
principally in the pupal stage. 
Adults of cadaverina may be found in houses during early 
spring and late fall, especially in kitchens, pantries, or cellars. 
In the District of Columbia they often occur in considerable 
