DISEASES OF INSECTS. 217 



denominated Principes> because of the wonderful instincts 

 of ants, wasps, bees, and other gregarious tribes that be- 

 long to it ; and they merit a name of honour not less for 

 the benefits that they confer upon mankind, by keeping 

 within their proper limits the various insect-destroyers 

 of the produce of the globe. It deserves notice that 

 when these latter increase to a degree to occasion alarm, 

 their parasites are observed to increase in a much greater, 

 so as to prevent the great majority of them from breed- 

 ing a . Though these benefactors of the human race con- 

 stitute numerous genera, at. present not well ascertained, 

 I shall speak of most of them under the common name 

 of Ichneumon. 



The appearance of these little four-winged flies puzzled 

 much the earlier naturalists : that a caterpillar usually 

 turning to a moth or butterfly should give birth to my- 

 riads of jlies 9 was one of those deep mysteries of nature 

 which they knew not how to fathom b : even the pene- 

 trating genius of our great Ray, though he ultimately 

 ascertained the real fact c , was at one time here quite at 

 fault ; for he seems at first to have thought, when from 

 any defect or weakness nature could not bring a cater- 

 pillar to a butterfly, in order that her aim might not be 

 entirely defeated, that she stopped short, and formed 

 them into more imperfect animals d . 



Before I detail more particularly the proceedings of 

 Ichneumons, I shall make a few general remarks upon 

 them. The structure of the instrument by which they 

 are enabled to deposit their eggs in their appropriate 

 station has been before sufficiently described e ; it is long 



a Reaum. ii. 439. b Ibid. 415. Mouffet 57. 



e Hist. Ins. Prsef. xv. A Cat. Cant. 137. 



* See above, p. 162. 



