OBJECTIONS ANSWERED. 



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prove that the study of insects may be productive of consi- 

 derable 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 follows 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 prevent their ra- 

 vages ? Ignorance in this respect often occasions us to mis- 

 take our enemies for our friends, and our friends for our 

 enemies ; so that when we think to do good v/e only do harm, 

 destroying the innocent and letting the guilty escape. Many 

 such instances have occurred. You know the orange-coloured 

 fly of the wheat, and have read the account of the damage 

 done by this little insect to that important grain; you are 

 aware 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 mischief. ^ 

 Middleton, in his " Agriculture of Middlesex,^' speaking of the 

 Plant-louse that is so injurious to the bean, tells us that the 

 lady-birds are supposed either to generate or to feed upon 

 them.^ Had he been an entomologist, 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 to man, since no insects are greater 

 devourers of the Aphides. The confounding of the apple Aphis, 

 or American blight {^A. lanigera^,) 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 



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

 Gent. Mag. for August, 1795. This little insect produces no galls like many of 

 the species of the genus, (Latr. Gen. Ci'tist et Ins. iv. 253. Meig. Dipt. i. 94.) 

 yet it corresponds with the characters of Cecidomyia laid down both by Latreille 

 and Meigen. 



2 P. 192. 



3 See Latr. Families Naturelles du Regne Animal, 429. This insect has had 

 four generic names given to it, Lachnus by lUiger, Eriosovia by Leach, Myzoxyle 

 by Blot, and Schizoneura by Hartig in Germar's Zeitschr. f. d. Entomol. 



c 4 



