2 252 
they are closed, first, by a lining of silk, then by a thickened layer of 
the glue, and finally by silk which gives this median portion of the co- 
coon, inside, a paler coloring than the rest. In the cocoon of Bernbea 
obsolotus, which I have received from Mr. Coquillett from southern Cal- 
—ifornia, and which is composed of agglutinated sand, these perforations 
are smaller and in a single row of seven or eight encircling the middle, 
but they have a similar structure. 
The larva remains unchanged in this cocoon over winter, and trans- 
forms to the pupa state in the spring, shortly before the appearance of 
the mature insect. The pupa (Fig. 36 0, c.) resembles the mature insect in 
general appearance, but, as in all such cases, is soft-fleshed and whitish 
in color. It rapidly hardens and changes to the dark color of the imago, 
: which is ready in a few days to gnaw its way out 
of the pupal cell, and, passing through the bur- 
row made by the perfect insect the previous year, 
begins again the cycle of existence which its 
emergence has just completed. 
This, as I said before, will serve as a type of 
the development and life history of the other fos- 
sorial wasps, although they differ greatly in the 
style of burrow and form of cell which they make 
to protect their future progeny, and in the char- 
acter of the food with which they provision such 
cells. A most interesting article could, in fact, 
be written on the habits of these different species, 
Fic. 38.—a, cocoon of Sphecius 
natural size; b, enlarged some of which use spiders of various kinds, in- 
section of pore (original). 
cluding Tarantulas, while others use various soft 
larve, especially those of a Lepidopterous nature. Those who are 
interested in further details on the subject will find a popular exposition 
in the first volume of the American Entomologist, written mainly by mv 
associate on that journal, the late B. D. Walsh. 
If man could do what these wasps have done from time immemorial, 
viz, preserve for an indefinite period the animals he feeds on by the sim- 
ple insertion of some toxic fluid in the tissues, he would be able to rev- 
olutionize the present methods of shipping cattle and sheep, and to 
obviate much of the cruelty which now attends the transportation of 
live stock and much of the expense involved in cold storage. 
