THE HABITS OF MONODONTOMERUS. 99 
the cell. The majority, as was afterwards proved by what I have just stated, had crept 
out and distributed themselves over the room. Many probably had escaped into my other 
collecting boxes while being conveyed home. 
It was in the afternoon of the following day that I placed my larvæ of Monodontomerus 
with that of the bee, in the closed glass tube, as already mentioned; so that, in all pro- 
bability, it was during the few hours that my boxes which contained the young bees and 
their parasites remained near that which enclosed the cell, that these little creatures 
escaped and affixed themselves to the larvæ. "This was at a stage of existence when the 
whole brood of nondescripts had been recently matured, and probably soon after there had 
been communion of their sexes (?) within the cells,—if, indeed, males, which I have not 
been able to identify, are produced,—and before the bodies of the fertilized females, which 
the vesicles in the other cells, as well as those afterwards found on my larvæ, all proved 
to be, had begun to be enlarged. These diminutive objects I soon found to be Acari 
of a new type (fig. 7). 
I have said that the bladder-like bodies were fertilized females. There seems to be 
full proof of this in the following circumstances. At the time when I enclosed the larval 
Monodontomeri in the glass tube, the temperature of the atmosphere of the room was above 
55° Fahr., and very frequently during the ensuing fortnight was more than 60° Fahr. The 
growth of the Acari was then very rapid. Within ten days from the time when they affixed 
themselves, indeed within eight from my first observing them, the bodies of some were 
enlarged to the size of the head of a small pin, and the ova within them were readily and 
distinctly identified with the microscope. They increased in bulk most rapidly during the 
first fortnight, after which their enlargement was less perceptible. On the contrary, I fancied, 
but was not certain, that they became somewhat smaller. Several of them at first were 
more opake, and afterwards became of a brownish colour. In about three weeks, during 
which time the tube had been frequently exposed to the sun, there was full proof that some 
of these specimens had produced young. The interior of one end of the tube was then 
‘covered with a great number of Acari, such as I had originally seen in the bees’ nest (fig. 6) ; 
not with the abdominal portion of their bodies enlarged, but short, narrow, and somewhat 
tapering at its extremity. These little beings appeared to have only recently come forth, 
as they were of a much lighter colour, and somewhat smaller than those which were found 
in the cell. Some of them placed on a micrometer plate measured only sixteen thousandths 
of an inch in length. The glass tube being tightly stoppered with a cork, so that nothing 
could enter or escape, it was fair to conclude that these were the young of some of the 
females attached to the bodies of the larvæ, although I neither saw them come from their 
parents, nor was able to find that any ova had been deposited from which they might have 
been hatched. Nevertheless they had already undergone the change common to the tribe, 
—that of obtaining an additional pair of legs, as they had the full complement—four 
pairs. It is well known that this is not the condition in which Acari are usually pro- 
duced, each having at first but three pairs. It remains for future inquiry, therefore, to 
show in what condition this species first makes its appearance,—whether ova are at 
any time deposited and afterwards become hatched, whether ova are produced at one 
season and living young at another, or whether, as I have most reason to conclude, the 
