1897.] Entomology. 81 
specimens of these bees are found. Their position is uniform; the twig 
or thorn is grasped tightly with all of the six legs, and, in addition the 
mandibles are widely opened and with their tips firmly inserted into 
the wood. It requires some force comparatively speaking to dislodge 
the bees from their position. * * * On the very first day I found that 
there are certain dead shrubs which serve as sleeping quarters for a 
multitude of the bees. In the course of time I discovered within a 
short distance four shrubs (or dwarf trees) upon each of which from 50 
to 70 specimens of the sleeping bees could be seen every morning, 
and several other shrubs which harbored a smaller number of specimens 
with plenty of room for more. Here my third species the Sphegid 
Coloptera wrightii comes in. It was always on the sleeping trees in 
company with the bees, but not so numerous as the latter. I neversaw 
it asleep at the hour I made these observations, but the specimens were, 
like watchmen, slowly walking up and down the twigs, over the bodies 
of the sleeping bees, carefully and deliberately touching and examining 
with their antennz the bees, as if trying to arouse them from their 
sleep. If I had been on the spot at an earlier hour I would no doubt 
have ascertained also the sleeping habit of the Coloptera. A well- 
frequented sleeping tree presents a very striking and exceedingly pretty 
sight, which I never wearied of observing day after day.” 
Effectiveness ofa Net in Excluding Insects.—-Prof. F. Plateau 
has made a number of interesting experiments as to the effectiveness 
of a net in excluding insects, although the meshes were wide enough to 
allow their passage. His conclusions are: (1) A stretched net does 
not absolutely stop the flight of insects. (2) In their flight the insects 
behave as if they did not see the meshes. (3) Direct passage during 
flight is always rare; in most cases the insect stops and scrambles 
through, if at all. (4) The explanation is to be found in the lack of 
precision associated with compound eyes; the threads of the net, like 
etchings on an engraving produce the illusion of a continous closed 
surface.—Journal Royal Mier. Society. 
Life-History of the Peach-tree Borer.—There is but one gen- 
eration of larvæ of Sannina exitiosa annually. The moths appear as 
early as May in the latitude of Washington, D. C., and southward, 
over what approximates the lower austral region. In the upper austral 
region, roughly comprising the States above the cotton belt and below 
the northern tier, the moths do not appear until after the middle of 
June. In the transition region, which comprises the northern tier of 
States, together with most of New York and New England, the moths 
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