164 The American Naturalist. [February, 
These insects, though very abundant, have been very little studied, 
and little is known of their life habits. They often multiply in extraor- 
dinary numbers, especially in moist situations, swarming on the surface 
of stagnant water or on wet soil. They seem to be very tolerant of 
cold, and we have interesting accounts of the occurrence of a species 
related to this one in the Arctic regions on melting snow fields . 
and on glaciers, where they are known as “snow fleas” or “snow 
worms.” Other interesting forms occur in caves, and in the Mammoth 
Cave in Kentucky they are notably abundant. In houses they may 
often be found on window sills, in bathrooms, and sometimes, under 
favorable situations, in very considerable numbers. Especially are 
they apt to occur where there are window plants or in small conserva- 
tories, but are not confined to these situations. Very little is known 
of their food habits, but they are supposed to subsist on refuse or chiefly 
decaying vegetable matter. 
The striking peculiarities of these insects are in the remarkable 
ventral tube and the strong saltatorial appendage of the extremity of 
the body. The first arises from the forward body segment, and seems 
to act in this species as a sort of a retainer for the leaping organ, OF 
spring proper. It is said to secrete a viscid fluid, which enables the 
insect to better adhere to smooth vertical surfaces. The so-called 
“catch,” or retainer proper, is shown in a small projection between the 
hind pair of legs and the spring, and grasps the latter near the middle. 
The springing organ is two-jointed, the last joint being bifurcate, and 
its terminals inclosing the ventral tube. 
These insects can not survive dryness, and, while they will not often 
occur in sufficient numbers to be particularly objectionable, the Te 
moval of the moist objects or surfaces on which they congregate and the 
maintenance of dry conditions will cause them to soon disappear.—C. 
L. Maruartrt in Bulletin, No. 4, U. S. Division of Entomology. 
Sphinx Caterpillar Surviving Ichneumon Attack.—Rev. T. 
A. Marshall records’ an interesting case of this kind. A caterpillar of 
Acherontia atropos had been ‘forced’ by artificial warmth to an early 
development of the moth. The latter was a perfect specimen ; in 1ts 
abdomen was found a large Ichneumonid larva. “ From the caterpillar 
point of view we have here only an instance of tenacity of life under 
trying circumstances. * * * In the normal course of things the death : 
of the Atropos larva after its change to a chrysalis, and the production 
of a living ichneumon, would inevitably have taken place sometime 
2Ent. Monthly Mag. Dec., 1896. 
