Famimy CALLIPHORIDAE Bq 
often indistinct about the ‘‘button’’ area. The two oval apertures 
are distinctly separated. Third-instar larvae have each posterior 
spiracle with three slitlike, nearly parallel apertures, the peri- 
treme is distinct, and the ‘‘button,’’ if present, is obvious. 
The cephaloskeleton (pls. 83B, 34H, or 48D) which lies within 
the first to third segments, is divided into paired sclerotized ar- 
ticulated segments. The labial sclerite (lsc) is that portion of 
the cephaloskeleton which is curved or hooked ventrally and acts 
as a tooth or mandible. Immediately below is the minute dentate 
selerite (dsc). An unpaired accessory sclerite (alsc) lies between 
the paired labial sclerites in some species; this is present in the 
Calliphorini, not in the Luciliini. Articulating with and posterior 
to the labial sclerite is the hypostomal sclerite (hsc) which in 
turn articulates with the pharyngeal sclerite. Immediately below 
the hypostomal sclerite is a small infrahypostomal sclerite (ihsc). 
The pharyngeal sclerite is winged and is the hindmost as well 
as the largest of the sclerites composing the buecopharyngeal ap- 
paratus. This is divided into an upper and lower wing which are 
termed dorsal (dc) and ventral (vc) cornua; the anterodorsal 
prolongation is termed the dorsopharyngeal sclerite (dphsc) or 
dorsal arch; a ribbonlike parastomal (pssc) or suprahypostomal 
selerite extends dorsally over the hypostomal sclerite. 
The posterior cavity (pl. 84G, pc) has three pairs of tubercles 
on the dorsal margin; these are termed inner (7), median (m), 
and outer (0) pairs. The lower border is provided with three or 
four pairs of tubercles and these are designated in the same way. 
The anal protuberance (pl. 34G, ap) has two prominent tubercles 
between which lies the anal opening. 
The posterior spiracles lie within the so-called posterior cavity, 
‘and each is partially (pl. 34D) or completely (pl. 42D) sur- 
rounded by sclerotized peritreme (p) in the third instar. The 
sear produced by the casting of the external portion of the spir- 
acle in the previous instar is called the ‘‘button’’ (6), and this 
may or may not be evident. The ‘‘button’’ is obvious within the 
peritreme in the Calliphorinae, not in the Chrysomyinae. The 
position of the two or three more or less oval and nearly paral- 
lel slitlike apertures yields characters of considerable signifi- 
cance, but the ornamentation within the slits is of apparently no 
taxonomic value. The so-called ‘‘sun-ray’’ structures, or peri- 
stigmatie glands (of Keilin, 1975), have usually been omitted in 
the illustrations. 
LARVAL HABITS. The larvae of most blowfly species are 
saprophagous and are usually found feeding upon decomposing 
substances, most often flesh. Decomposing flesh, however, is not 
