1871.) 951 
cell, stored with green grubs, it contains a young larva of C. neglecta, 
busily eating that store, and no trace remains of the egg or larva of 
Odynerus.” 
I therefore especially directed my attention last summer to cells 
in process of construction or recently closed cells, and, having at hand 
one or two localities where O. spinipes was abundant, I examined a 
considerable number of these. I used to dig in the bank where they 
were constructing their cells, and, on opening one, turn its contents 
carefully out, and examine them and the wall of the cell. It not 
unfrequently happens, that, in opening a cell, the portion of wall 
removed and usually lost is that to which the egg of spinipes is affixed ; 
- and this source of error in the following observations must be remem- 
bered when it is stated that no trace of spinipes was found. 
There are two matters in relation to the nidification of O. spinipes 
that may as well be noted, as they enable us to understand the remark- 
ably rapid development of the larva of O. spinipes, and especially of 
C. neglecta, and also why the green grubs are preserved so fresh and 
plump until they are eaten; whereas, when removed from the cell, and 
kept, say in a pill-box, they speedily die and desiccate. 
One of these points is, that, in removing the earth to form her cell, 
O. spinipes wets it freely, so as to soften it and admit of its being 
scraped into pellets; and, as a result, much of the moisture so 
applied soaks into the earth, so that each cell is surrounded by a zone 
of damp earth of a quarter of an inch in thickness. The other point is, 
that the place of nidification is always a bank freely exposed to the 
sun, often at such an angle that for part of the day it has a vertical 
sun, and in such a recess of the bank that the surrounding parts reflect 
and concentrate the heat upon it. The result is, that the cells must 
have a very high temperature, with a moist atmosphere that probably 
intensifies its effects. 
I found altogether a considerable number of larve of neglecta 
newly hatched, but in only one instance did I meet with an egg; 
whether this was an egg of C. neglecta or of C. ignita, I cannot 
positively say, as the larva when full-fed was not placed in circum- 
stances to make it spin a characteristic cocoon (which it can only do 
in a cell of similar size and shape to that of the wasp), and it after- 
wards died. It is, however, extremely probable that it was C. neglecta, 
as that species is so much more abundant than O. zgnita in the cells 
of O. spinipes. 1 do not, however, consider the point as of extreme 
importance, as it seems almost certain that the habits of C. cgnita and 
of O. neglecta, as parasites of O. spinipes, are the same. 
