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 larvae 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 larvae. 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 larvae, 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 larvae, 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 



