80 
insects when excavating their burrows. These nest-tunnels are 
often driven to a depth of several inches, and all the soil to be 
removed is brought to the surface by means of the enlarged and 
rather flattened coxae which act like hoe-heads beneath the body 
and drag the soil along the floor of the tunnel as the animal 
backs up to daylight from the dark recesses of her gallery: the 
close apposition of the middle pairs of coxae ensures that very 
little soil slips between to be left behind.” A few pompilids, 
however, are satisfied with making no nests of any kind. Hart- 
man (1905) speaks of a brilliant blue Texas pompilid which de- 
posited her spider prey on the margin of her own web, laid an 
egg upon it and left it to fate. Sharp (1901) speaks of Emery, 
who states that some pompilids merely sting and parasitize but do 
not bury their prey. 
A curious relation exists between Pompilus pectinipes V. de L. 
and P. rufipes L. and argyrolepis Costa. Ferton (1905) studied 
the habits of these insects in Bonifacio. He found that P. rufipes 
and argyrolepis, as is usual in the genus Pompilus, store their 
burrows with spiders which they themsely es capture, but the 
related P. pectinipes has parasitic habits, for it evidently smells 
out the closed burrows of the foregoing species, digs them up, 
removes the wasp egg from the spider’s abdomen and, laying her 
own in its place, refills the burrow. Ferton thinks that the para- 
sitic habit of pectinipes is a comparatively recent acquisition, for 
the insect, unlike the pompilid Ceropales, is still armed with a 
good sting and legs fitted for digging. 
The genus Ceropales is parasitic on the genera Pompilus, 
Pseudagenia and probably others, and is more or less specialized 
or modified for her work. According to Adlerz (1903), Cero- 
pales watches the uneasy Pompilus dragging a spider homewards, 
and at an opportune moment runs up and lays her egg in one of 
the cleft-shaped stigmata or breathing pores of the spider’s abdo- 
men. Subsequently Pompilus oviposits on this spider and buries 
it, but her own young is soon overcome by the Ceropales grub, 
which, hatching earlier from its place of concealment, consumes 
all. I noticed a similar parasitism in the Philippines with Nan- 
thampulex (Ceropales) vs. Pseudagenia and Pompilus, but did 
not notice the oviposition of Nanthampuler. 
Spiders of many kinds are overcome by the Pompilidae. Pepsis 
formosa, the big “Tarantula Hawk” of the West and Southwest 
United States, has often come into literature because of its duels 
with the great spider, and both spider and wasp, mounted on 
cards, are included among the souvenirs sold to tourists who visit 
* An account of a battle between Pepsis and the spider in Texas is given by 
S. B. Buckley (1861). 
