INTRODUCTION. 



Non v' accorgete voi, che noi siam' vermi 

 Nati a formar T angelica farfalla ?" * 



Lepidopterous insects, like most others of their 

 class, are liable to be attacked by various parasitical 

 assailants, which effect a lodgment in the interior of 

 their bodies, the substance of which they speedily 

 consume, and thereby destroy them in great num- 

 bers. In none of their different stages are they ex- 

 empt from these attacks, excepting perhaps in their 

 winged state ; but they are particularly exposed to 

 them when caterpillars. The parasites are hyme- 

 nopterous flies belonging to the genus Ichneumon of 

 Linnaeus ; and perhaps the most destructive are those 

 minute kinds which compose the modern generic 

 group named Microgaster. As an example of the 

 latter, we have represented the species which de- 

 stroys the caterpillar of the common Cabbage But- 

 terfly : it is the Ichneumon glomeraius of Linn. 

 (Plate II. fig. 8, greatly magnified.) The size is 

 very diminutive, the largest specimen seldom ex- 

 ceeding two lines in length. The general colour of 

 the body is deep black, and the legs reddish-yellow. 

 The wings are somewhat longer than the body, and 

 pubescent, each of the upper pair having a triangular 

 black spot near the middle of the anterior margin (the 

 stigma), three discoidal cells, and a triangular areolet, 

 rather imperfectly formed. The abdomen is furnished 

 with an ovipositor, consisting of two flat valves, and 

 a curved horny sheath, terminating in a point. The 

 " Introd. to Entomology, i. p. 76. 



