145 
the two ends of its body remain largely in their first position and 
so the grub must buckle up, so to speak. Even later, when it chews 
up the spider’s legs, it retains a well-curved position. A large 
full-fed larva (Fig. 74) is about 18.5 mm. long, distinctly slender, 
thickset below the middle, and very well segmented by scallops in 
dorsal and lateral profile. The head is fairly large and bears 
stout, dark-tipped mandibles. The tip of the body is obliquely 
subtruncate and the thorax is armed with a few bristles. The 
general color is yellowish white, the gut is darker, while the end 
of the body is clear. The feeding larval stage is a little less 
than five days. <A large cocoon (Fig. 75) measures 24 mm. long 
by 4.3 wide; it is thin and shaped somewhat like that of the 
Sceliphronini, but has the fore end sharply squared off, whence, as 
elsewhere along its length, silken stays radiate to the cell walls. 
One or two thin discs may be spun first, just above the cocoon. 
The posterior end is bulb-like and its dark and shiny color con- 
trasts strongly with the pale brown or tan of the main portion. 
A female pupa measures about 19.5 mm. long; it is quite 
slender; the head and thorax are devoid of armature, but the 
abdomen bears spine-like processes and the legs are only weakly 
armed. The color is creamy yellow. 
My notes on this insect are for August-September, 1917.’ Other 
Trypoxylon may utilize beetle borings as a nesting place, and i 
found one wasp that had partitioned off a mud-dauber’s cell 
(Sceliphron) for her brood. 
CERCERIDAE. 
A family of thickset wasps with large heads and rather broad, 
well-marked constrictions between the abdominal segments. The 
widespread genus Cerceris is represented by numerous species, 
which generally prey on various species of beetles, weevils con- 
stituting the fare of one, leaf beetles of another, and so on. Fabre 
in speaking of the large European C. tuberculata has found its 
weevil prey weighs 250 mg., while the wasp itself tips the beam 
at only 150 mg. C. simplex of Brazil stores a tenebriomid beetle 
(Epitragus, Poulton, 1917). These wasps are excellent hunt- 
resses, and entomologists sometimes reap a harvest of rare 
beetles when they unearth the perfectly-preserved cell contents 
of a Cerceris colony. J. Knikel D’Herculais (1882) once ex- 
humed thirty nests of C. bupresticida and thus secured 450 speci- 
mens of buprestid beetles. 
As an entomologist, Cerceris is fairly good—that is, if she 
really strives to capture only related beetles, even if these be of 
very diverse size and form—but this group adhesion, however, 1s 
