[ 9 ] 
XI. Further Observations on the Habits of Monodontomerus ; with some Account of a 
mew Acarus (Heteropus ventricosus), a Parasite in the Nests of Anthophora retusa. 
By GEORGE Newrort, Esq., F.R.S., FLS. $c. 
Read March 5, 1850. 
AS some of the details of a paper on “certain Chalcidide and Ichneumonide,” which I 
had the honour of communicating to the Linnean Society, in March 1849, drew forth, at 
that time, the criticism and dissent of some entomologists who had paid considerable 
attention to those groups, I was desirous, during the past summer, of repeating my ob- 
servations, and, having the ascertainment of strict truth for my object, sought to correct, 
if erroneous, whatever might have been questioned, and to confirm by further observations 
what I had already correctly stated. Accordingly, on the 16th of September last, I 
revisited the spot at Gravesend, where, two years before, I discovered the larvæ which 
proved to be those of Monodontomerus, and of which an account was given in the paper 
above referred to. i 4 
On this second occasion I had the good fortune to obtain an abundance of these larvæ. 
Some idea may be formed of the number discovered by the fact that I brought away with 
me two hundred and forty-seven specimens, independent of many that were accidentally 
lost in the search. These larv were found, as on the previous occasion, in the closed cells 
of Anthophora retusa, either in those which still contained the larva (Tas. X. fig. 1) or 
nymph (fig. 2) of that bee, or in others in which the original inmate had been destroyed. 
The number of larvæ of Monodontomerus found in the first five cells opened was nineteen 
in the first; twenty-three in the second; thirteen in the third ; nineteen in the fourth, 
and thirty-four in the fifth. In each of these cells I had full proof that the parasites had 
fed on the Anthophora itself, as stated by another observer in correction of my first sup- 
position, and as I had already been convinced by examination of the organs of nutrition. 
The emptied and dried-up tegument alone was all that remained of the body of the 
original inhabitant in each cell. In order however that there should be no mistake on 
this fact, I removed three of the cells, which contained larvæ of Monodontomeri, without 
opening them further than to ascertain the presence of the parasites, and placed each in 
a separate small box to examine the contents at leisure, and more accurately than I could 
do on the spot. This examination was made on the following day, and each cell was then 
found to contain the dried-up remains of a single larva of Anthophora, with a variable 
number of the larvæ of Monodontomerus,—nineteen in the first cell, twenty-three in the 
second, and thirteen in the third as just stated. In neither of these instances had the 
parasites been contained or fed within the body of the bee-larva, but had exhausted it 
from without, and had drained the body of its contents in the same way as the larva of 
Paniscus drains that of the body of the caterpillar. In those cells in which the parasites 
were of largest size, the remains of the bee-larvze had been most completely exhausted ; 
while in two of the cells the tegument was still soft, and not quite emptied, but in each 
02 
