Observatio7is on Insects affecting the Turnip Crops. 59 



men spindle-shaped and pitchy in colour, attached to the trunk by 

 a narrow ochraceous petiole; wings four, iridescent; superior, 

 with a narrow fuscous stigma, from which issues beneath a short 

 curved nervnre, and there is a large elongate-trigonate cell at the 

 base ; legs, six, slender and bright ochreous, variegated with dark 

 brown; length, 1| line ; expanse of wings, 2^ (fig. 18 q). 



As there are many generations of these flies in a summer, it 

 follows that they are most formidable enemies to the plant-lice ; 

 and Providence, watchful of all his works, and regarding in the 

 smallest as well as the greatest that balance which preserves the 

 order of the universe, to avert the total annihilation of the feeble 

 Aphides, has provided numerous other parasitic flies to destroy the 

 destroyers, and again keep them in check. The jlpliidii are such 

 constant attendants upon infested plants, that I scarcely ever 

 notice any unaccompanied by the horny shells of the defunct plant- 

 lice ; and even in a green-house I have seen nearly as many of 

 these parasites as there were of the Aphides. 



It is impossible to advance a step in the natural history of in- 

 sects without finding so much to interest and admire, that it is 

 difficult to refrain from entering fully into the subject : fearing, 

 however, that I may become tiresome to the general reader, I 

 will allude as briefly as possible to the little flies which destroy 

 the maggots of the full-fed Aphidii, glutted with the vitals of the 

 plant-lice : they are all Hymenoptera ; and whilst they fly about 

 to reconnoitre the aphides, no sooner have they met with one that 

 contains a maggot than they pierce the already indurated shell, 

 and deposit an eg^ within : as soon as it hatches, it commences 

 feeding upon the parasitic maggot, or more probably on the 

 quiescent pupa ; and instead of an Aphidius, one of the following 

 insects bursts from its dark tomb, namely, Ceraphron Carpenteri, 

 Cyrfogaster vulgaris* and Colax aj^hidiirY 



8. Ceraphron (Megaspilus) Carpenteri, Curtis.'^ Black, head 

 and thorax pubescent; body shining; horns long in the male, 

 and eleven-jointed, the joints hairy, and more or less serrated, 

 excepting the two first and the last ; simply clavate in the female ; 

 wings, four, with a large brown semiorbicular stigma on the su- 

 perior, from which issues a short curved nervure, being the 

 only one ; legs pitch-colour, apex of thighs, the shanks and feet 

 ochraceous; length, two-thirds of a line; expanse If. 



I have frequently bred this insect from aphides, containing, no 

 doubt, the parasitic Aphidii. 



9. Cyrtogaster vulgaris, Wcdker.^ Female with clavate black 



* Also Coruna clavata of Walker, in Eiit. Mag., vol. i. p. 380. 



t Curtis's Brit. Ent., pi. and fol. 1G6. 



X Curtis's Brit. Ent., fol. 249, and Guide Gen. 581, 7. 



§ Ent. Mag. vol. i.,p.382; Curt. Guide Gen., G24, 1. 



