232 Trans. Acad. Sci. of St. Louis 
even protruding from the bee burrows, were these shed- 
ding skins adhering conspicuously. This indicated just 
which species were probably their hosts. That they 
were quite numerous I was also certain, since I picked 
up more than sixty of these shedding-skins, and of course 
these were not all. 
While there is sufficient evidence that these para- 
sites prey upon the inhabitants, and while they spend 
most of the sunshiny hours each day in flying to and 
fro before the openings of the burrows or resting near 
by, and although I have watched for hours at a time, I 
have never yet seen one of these creatures attempting 
to enter a burrow. I especially watched for this, since 
the great Fabre has discovered for another species of 
this genus some complicated aspects of life history. 
True I have often seen the females hovering over a bur- 
row, poising on the wing above the aperture and dipping 
down again and again, much in the manner of a dragon- 
fly depositing her eggs under the water, and I suspected 
that with each dip she deposited an egg but, like Fabre, 
I have never discovered the egg. Fabre seems to think, 
for his species, that the parent fly oviposits by merely 
dropping a minute egg while flying over the surface of 
the mud walls which contain the grubs of the host, and 
that the larvae hatching from the eggs are wonderfully 
adapted for breaking into the masonry to reach the host 
by being provided with a very horny, deflexed head, 
armed in front with stiff bristles and under the body with 
several pairs of elongate setae serving as organs of 
locomotion. In the species under present consideration, 
the eggs are probably deposited in this manner, although 
some other species of this genus, as A. oedipus, ate 
known to enter the bee burrows. Several females of A. 
