208 DISEASES OF INSECTS. 



as a reproduction, but it seems rather a malformation. 

 Miiller mentions a most extraordinary fact of one of the 

 Noctuidtf, which when disclosed from the pupa retained 

 the head of the larva a . One of the most remarkable 

 instances of this kind that have fallen under my own 

 observation, may be seen in a specimen of Chrysomela 

 hcemoptera in the cabinet of our friend Curtis ; in which 

 one of the thighs produces a double tibia, but only one 

 of these is furnished with a tarsus. 



The diseases of insects which arise from some internal 

 cause are not very numerous. The first that I shall 

 mention is a kind of vertigo. " Ants have also their 

 maladies," says M. P. Huber : " I have noticed one ex- 

 tremely singular; the individuals attacked by it lose their 

 power of guiding themselves in a straight line, they can 

 walk only by turning round in a circle of small diameter 

 and always in the same direction. A virgin female shut 

 up in one of my glasses was seized on a sudden with this 

 distemper ; she described a circle of an inch in diameter, 

 and made about a thousand turns in an hour, or not 

 quite seventeen in a minute. She continued constantly 

 turning round for seven days, and when I visited her in 

 the night I found her still in motion. I gave her honey 

 and I think that she ate some of it." He observed 

 that some workers were attacked by a similar disease : 

 one of these, however, had the power of walking from 

 time to time in a straight line ; when placed upon its head 

 it continued its gyrations b . Similar motions of a little 

 moth, mentioned on a former occasion , may perhaps 

 have been produced by the same cause. Bees are also 



a Naturf. xvi. t. iv./. 13. h Huber Fourmu, 174. note 1. 



c VOL. II. p. 365. 



