DIPTERA. 479 



the beards, and he says he saw great numbers of them on the 

 ground."* From these observations, and from remarks to the 

 same effect, made to me by intelligent farmers, it appears that 

 the descent of the insects is facilitated by falling rain and 

 heavy dews. 



Having reached the ground, the maggots soon burrow under 

 the surface, sometimes to the depth of about an inch, those of 

 them that have not already moulted casting their skins before 

 entering the earth. Here they remain, without further change, 

 through the following winter. During the month of May, I 

 have seen specimens still in the larva form, in the earth wherein 

 they liad been kept during the winter. It is not usually till 

 June that they are transformed to pupa. This change is ef- 

 fected without another moulting of the skin ; not the slightest 

 vestige of the larva-skin being found in the earth in which 

 some of these insects had undergone their transformations. 

 Moreover, the pupa is entirely naked, not being enclosed either 

 in a cocoon or in the puparium formed of this outer skin of 

 the larva, and it has its limbs and wings free or unconfined. 

 The pupa state lasts but a short time, a week or two at most, 

 and probably, in many cases, only a few days. Under the 

 most favorable circumstances, the pupa works its way to the 

 surface, before liberating the included fly; and when the insect 

 has taken wing, its empty pupa-skin will be seen sticking out 

 of the ground. In other cases, the fly issues from its pupa- 

 skin in the earth, and comes to the surface with flabby wings, 

 which soon expand and dry on exposure to the air. This last 

 change occurs mostly during the months of June and July, 

 when great numbers of the flies have been seen, apparently 

 coming from the ground, in fields where grain was raised the 

 year before. Some persons have stated that the insects are 

 transformed to flies in the ears of the grain, having probably 

 mistaken the cast-skins of the maggots found therein for the 

 shells of the chrysalis or pupa. 



Several cases of the efficacy of fumigation in preventing 

 the depredations of these insects are recorded in our agricul- 



* " New England Farmer," VoL XVI., p. 61. 



