OBJECTIONS ANSWERED. 29 



to man, since no insects are greater devotirers of the 

 Aphides. The confounding of the apple Aphis, that has 

 done such extensive injury to our orchards, with others, 

 has led to proceedings still more injurious. This is one 

 of those species from the skin of which transpires a white 

 cottony secretion. Some of the proprietors of orchards 

 about Evesham, observing an insect which secreted a si- 

 milar substance upon the poplar, imagined that from this 

 tree the creature which they had found so noxious was 

 generated ; and in consequence of this mistaken notion 

 cut down all their poplars 3 . The same indistinct ideas 

 might have induced them to fell all their larches and 

 beeches, since they also are infested by Aphides which 

 transpire a similar substance. Had these persons pos- 

 sessed any entomological knowledge, they would have 

 examined and compared the insects before they had form- 

 ed their opinions, and being convinced that the poplar 

 and apple Aphis are distinct species, would have saved 

 their trees. 



But could an entomological observer even ascertain 

 the species of any noxious insect, still in ma^iy cases, 

 without further information, he may fall short of his pur- 

 pose of prevention. Thus we are told that in Germany 

 the gardeners and country people, with great industry, 

 gather whole baskets full of the caterpillar of the destruc- 

 tive cabbage moth (Noctua Brassicce, Fab.) and then bury 

 them, which, as Roesel well observes b , is just as if we 

 should endeavour to kill a crab by covering it with wa- 

 ter ; for, many of them being full grown and ready to 

 pass into their next state, which they do underground, 

 instead of destroying them by this manoeuvre, their ap- 



a Collet, in Month. Mag. xxxii. 320. b Roesel I. iv. 170. 



