356 APHIDES. 



resting, seemingly an immense migrating body : but, 

 slightly formed as they are, few creatures seem less 

 calculated for a distant removal ; and from whence 

 do they come ? Only two plants are in any way 

 remarkably infected with this insect ; and it seems 

 singular that these two, so different in their cha- 

 racters and nature, should commonly be equally 

 sufferers at the same time, which I believe they 

 are the bean-plant and the hop ; the former we 

 do not cultivate to an extent sufficient to give being 

 to such numbers, and the hop-grounds of Worcester 

 and Hereford are too distant (having an adverse 

 wind) to inundate us with these moving myriads. 

 It is more probable that the late rains have given 

 such a vigour to the bean-plant as to render its 

 circulating juices unpalatable to the creatures 

 abounding on them ; and hence I conjecture they 

 have left the districts where this legumen is exten- 

 sively cultivated in Somersetshire, and journeyed 

 from a distance of, perhaps, fifteen miles, with the 

 wind, in search of more suitable provender. But 

 the appearance and generation of insects, and this 

 race in particular, are involved in much mystery : 

 plants growing in houses, removed from all con- 

 nexion with those that are infected, will yet regu- 

 larly produce them the cinerarias universally, and 

 one species, c. cruenta, most remarkably so. This 

 is a plant whose herbage annually dies down to the 

 root, and hence has no vegetation remaining to 

 conceal eggs, if there were any ; for these creatures 

 bring forth their young alive, in all the cases in 



