PARASITIC HYMENOPTEIIA. 99 



Sp. 28. A. lutescens. Fern. Luteus oculis et antennis nigris, 

 vertice, lituris tribus scuti, scutello, metathorace et petiolo 

 fuscis. (Long. .13 ; alar. .24.) 



Fein. — Statura et magnitude) A Rosce : antennarum scapus lutes- 

 cens : alas ut in illo : pedes immaculati : abdominis segmenta 

 anteriora dorso tranversim infuscata. d 



Sp. 29. A. Avenae. Fem. Niger pedibus anticis et geni- 

 culis rufo -piceis, stigmate anoque ferragineis, antennis 

 17-, 18-articulatis. (Long. .12— .15; alar. .20— .24.) 



Bracon picipes . Ess. B. M. V. 28. Sp. 42? 

 Aphidius picipes . Ess. Act. Acad. ? 



Fem. — Os lutescens, palpi subfusci : alae hyalinae stigmate rufo- 

 ferrugineo, in exsiccatis piceo, nervis fuscis, radice et squamulis 

 piceis : pedes nigro-picei, antici femoribus tibiisque rufo - piceis 

 aut lutescentibus, latere externo fusco-lineatis, posteriores tro- 

 chanterum apice tibiisque basi et apice concoloribus : abdomen 

 nigro - piceum segmenti secundi medio pallescente, ano rufo- 

 ferrugineo. — Mas, palpi nigro-picei : antennae 20 — 22-articulatse : 

 pedes obscuriores : anus haud ferrugineus : A Rosce $ simillimus. 



Habitat in Aphidibus Avence passim omnium vulgatissimus. e — 

 (Mus. Soe. Ent.) 



Aphidum, Geoffr. II. 305. 26. Cyrtogaster vulgaris, Walker, Ent. Mag. I. 382, &c.) 

 select for the nidus of their progeny those Pucerons within which the grub of the 

 Aphidius, or of its fellow-devourer, Cynips erythrocephala, (Jur.) is silently 

 gorging, and the destroyer becomes the destroyed in turn. Some of these last 

 (Coruna clavata, Walk. Ent. Mag. I. p. 386), not content with the covering which 

 protects the Aphidius to its final change, when they are full fed leave the cavity, 

 and spin a white silky web between the belly of the Puceron and the leaf, and in 

 this undergo their transformation. Max. Spinola has given occasion to some 

 confusion, by appropriating to a species of Microgaster, synonyms and observa- 

 tions which belong to insects of the present genus. The accurate account of their 

 habits, long since given by Frisch, Cestoni (in Vallisnieri's works), and De Geer, 

 might be supposed sufficient to have cleared up this mistake which has been 

 pretty generally followed, the Linnsean Ich. Aphidum being, however, replaced 

 in its proper station by Fallen and Curtis. — On this account, I have ventured to 

 reiterate the detail from my own observations. The Pucerons, to which these 

 relate, abound on almost every rose of our gardens, except the sweet-briar, which 

 nourishes a distinct species, and its peculiar parasite. 



d I should have been inclined to consider this as an immature variety of 

 A. Rosce ; but that individuals of this last have assumed their characteristic tints 

 before they are disclosed from the puparium. 



e I have observed the proceedings of this species, which are precisely similar 

 to those of A. Rosa: ; the Pucerons pierced by it are found adhering to the grains 

 of oats, the flower-heads of Hypocharis radkala, &c. 



