246 THE BLOWFLIES oF NortH AMERICA 
Larva. First instar: Spines heavily pigmented as in caeru- 
lewwiridis and silvarum; segments 1 to 8 each with a complete 
band of spines at anterior border; segments 10 and 11 provided 
with posterior border of spines on dorsal surface; segment 9 
with bands of spines at both anterior and posterior margins 
narrowly interrupted. Tubercles on last segment and cephalo- 
skeleton similar to those of allustris. 
Second instar: Spines forming a complete band at anterior 
border of each of segments 2-8 and extending almost to dorsal 
surface on segment 9; segments 11 and 12 each usually with 
complete band on posterior border (sometimes restricted to 
ventral, lateral, and dorsolateral surfaces). Relative distribu- 
tion of tubercles on last segment as in third instar. Tubercles 
broadly rounded at tip, the median pair on upper border and 
inner pair on lower border only slightly smaller than the 
others. Cephaloskeleton (pl. 40, E) similar to that of caerulet-- 
viridis but labial sclerites more slender, the basal portion with 
a longer posterodorsal projection. Anterior spiracles with six 
to eight branches. 
Third instar: Distribution of spines variable; anterior margin 
of each of segments 2-8 generally completely encircled with 
spines (in some specimens the complete band may extend to seg- 
ment 9, while in others it may extend only to segment 7); pos- 
trior margin of segment 11 generally provided with three to 
four dorsal rows of spines, but spines sometimes absent at pos- 
terior margin of all but segment 12. Tubercles (pl. 40, G) out- 
lining stigmal field rather prominent; inner pair on upper 
border equal to or only slightly larger than the other two pairs 
which are nearly equal in size; on lower border, outer and inter- 
mediate pairs large, the inner pair comparatively large (in 
other species the inner tubercles on lower border are always 
distinctly smaller). Posterior spiracles (pl. 40, D) with peri- 
treme narrow and not heavily pigmented; a rather long narrow 
inward projection of peritreme between inner and lower spiracu- 
lar apertures. Pharyngeal sclerites (pl. 40, F') similar to those 
of caerulerviridis but with shorter ventral cornua. Anterior 
spiracles in one series with 5 to 8 branches (in a total of 24 
spiracles, 1 had 5 branches, 7 had 6, 12 had 7, and 4 had 8); in 
another, with 6 to 11 branches (total of 84 spiracles distributed 
3, 28, 33, 15, 4 and 1); size of lobes and form of spiracles as in 
sericata. 
Most of the series in the National Museum collection are from 
Brewster’ County, Reagan Wells, Dallas, and Uvalde, Tex. 
It is not an abundant species in North America except in the 
