28 OBJECTIONS ANSWERED. 



ceed further to prove that the study of insects may be 

 productive of considerable utility, even in this view, and 

 may be regarded in some sort as a necessary or at least 

 a very useful concomitant of many arts and sciences. 



The importance of insects to us both as sources of good 

 or evil, I shall endeavour to prove at large hereafter ; but 

 for the present, taking this for granted, it necessarily fol- 

 lows that the study of them must also be important. For 

 when we suffer from them, if we do not know the cause, 

 how are we to apply a remedy that may diminish or pre- 

 vent their ravages ? Ignorance in this respect often oc- 

 casions us to mistake our enemies for our friends, and 

 our friends for our enemies ; so that when we think to do 

 good we only do harm, destroying the innocent and let- 

 ting the guilty escape. Many such instances have oc- 

 curred. You know the orange-coloured fly of the wheat 

 ( Tipida Tritici, Kirby in Linn. Trans. Cccidomyia, Latr.), 

 and have read the account of the damage done by this 

 little insect to that important grain ; you are aw r are also 

 that it is given in charge to three little parasites to keep 

 it within due limits ; yet at first it was the general opinion 

 of unscientific men, that these destroyers of our enemy 

 were its parents, and the original source of all the mis- 

 chief a . Middleton, in his " Agriculture of Middlesex" 

 speaking of the Aphis that is so injurious to the bean, 

 tells us that the lady-birds are supposed either to gene- 

 rate or to feed upon them b . Had he been an entomolo- 

 gist, he would have been in no doubt whether they were 

 beneficial or injurious : on the contrary, he would have 

 recommended that they should be encouraged as friends 



a Kirby, in Linn. Trans, iv. 232. 235. See also a letter signed C, 

 in the Gent. Mag. for August 1795. b P, 192, 



