DISEASES OF INSECTS. 201 
only half the length of the other*; which he regarded as a 
reproduction, but it seems rather a malformation. Miul- 
ler mentions a most extraordinary fact of a Noctua, which 
when disclosed from the pupa retained the head of the 
larva». One of the most remarkable instances of this kind 
that have fallen under my own observation, may be seen 
in a specimen of Chrysomela hemoptera 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®. Similar motions of a little 
= Watunf, xi. 224. t. vf. 8. >» Ibid. xvi. t. iv. f. 1—3. 
° Huber Fournis, 174. note |. 
