228 THE BLOWFLIES oF NortH AMERICA 
vein near middle of second section of fourth vein; upper squamal 
lobe white at base, brown apically; lower squamal lobe brown. 
Abdomen colored like thorax, thinly whitish in certain lights 
especially on venter; first segment metallic and dark brown; 
second segment with a faint indication of a middorsal spot. on 
the anterior margin and with a marginal row of fine and hardly 
apparent bristles, these longer laterally; third segment with long 
erect marginal bristles; fourth segment with long erect scattered 
hairs and a marginal row of bristles. Fifth sternite (fig.98,B) 
as illustrated. 
Genital segments black metallic, of medium size, apparent in 
profile with abdomen in repose, and with scattered erect black 
setae. Internal anatomical features (pl.28,G and H) as illus- 
trated. 
Female. Head height 10.2; eye height 7.38; head width 13.0; 
bucea 0.37 of eye height; length of head at antenna 5.9 and at 
vibrissa 6.3; parafaciale opposite lunule 1.4 in width; vibrissae 
set 2.6 apart; front at narrowest 0.32 of head width, only slightly 
wider at vertex and 0.35 at lunule, the margins almost parallel 
anteriorly to about 1.5 above lunule; third antennal segment 
3.8 times:as long as second; palpus 3.7 in length. Wing with 
costal sections 2 to 6 in the proportion 76:50:94:38:10. Other- 
wise similar to male except for normal sexual differences. 
An extra lateral scutellar bristle often occurs on one side 
(rarely on both sides) between the basal and the median lateral 
bristle. Northern specimens seem to develop such adventitious 
bristles more often than specimens from the southern part of 
the species range. The normal number of lateral bristles in 
Lucilia is three. 
Length. 6-9 mm. 
Distribution. Holaretic. In North America from southern 
Canada to northern Mexico; common in the middlewestern part 
of the United States. 
Biology, habits, and immature stages. Egg. Wardle (1930, p. - 
561) stated that Lucilia illustris seems to be less sensitive to 
light than Phaenicia sericata and that it will oviposit when the 
sky is overcast. Eggs are often deposited upon decaying meats, 
and during the summer in the middlewestern United States car- 
casses of animals are usually blown by this species in competition 
with Phaenicia sericata. “ 
Larva. First instar: Distribution of spines rather difficult to 
determine owing to lack of pigmentation on some of the seg- 
ments; segments 2-9 each bordered anteriorly with a complete 
band of spines; segment 8 with spines lighter in color on lateral 
