310 THE BLOWFLIES OF NortH AMERICA 
again be found in considerable numbers. It is among the last 
of the blowfly species to disappear in the fall. 
Biology, habits, and immature stages. Egg. Uength approxi- 
mately 2.0 mm., diameter, 0.75 mm.; translucent white, feebly 
striate; elongate ellipsoidal, smaller at anterior and broader at 
posterior end, the ventral surface slightly curved, the dorsal 
surface flattened or slightly concave; micropyle at anterior end 
situated in a cuplike depression in the chorion, this prolonged 
into a groove which extends along the dorsal surface almost to 
posterior end. 
About 180 eggs may be deposited at one time although the 
usual number is considerably less than this. A total of 540 to 
720 eggs may be deposited during the lifetime of an individual 
female. Brown (1936) found the incubation period to be about 
11 hours at a temperature ranging from 25-35° C. with a 40 
percent relative humidity. , 
Larva. First instar: Spinose bands very narrow, the spines 
weak and not pigmented, apparent only on anteroventral mar- 
gins of segments. Segments 2 to 7 with complete anterior 
bands; segments 6 to 11 with posterior spinose bands, those on 
~segments 6 to 8 or 9 not continuous over dorsum and those on 
segments 6 and 7 very narrow. All spines with dome or wedge- 
shaped tips. Metapneustic; posterior spiracles each with two 
ovate orifices which appear more or less united basally, the 
peritreme hardly apparent toward ‘‘button’’ area. Cephalo- 
skeleton (pl. 44, B and C) slender, weak, the pharyngeal sclerite 
strongly arched, the dorsopharyngeal sclerite with a weakly 
pigmented process. 
Second instar: Segments 2 to 9 with complete anterior spinose 
bands, those on segments 8 and 9 weak and sometimes absent 
dorsally; segments 7 to 11 with posteroventral spinose bands, 
those on segments 8 to 11 complete; spines on dorso-posterior 
portion of segments weak; all spines larger and bands wider 
than in previous instar. Anterior spiracles each with 7 to 9 
(most often 8) circular orifices; cephaloskeleton (pl. 44, D) with 
labial sclerite strongly arched, hypostomal sclerite elongate, 
dorsal cornua long, weakly pigmented along dorsal margin, dorso- 
pharyngeal sclerite with pigmented process, ventral cornua 
truncate posteriorly and hghtly pigmented ventrally with ven- 
tral longitudinal grooves apparent. 
Third instar: Form stout, tapering anteriorly from sixth 
or seventh segments and slightly tapering posteriorly in the 
three terminal segments. Length from 6.8 to 18 mm., and 1.5 
to 3.5 mm. in width; fully matured larvae average about 17 
