Observations on Insects affecting the Turnip Crops. 61 



silky whitish pubescence ; the horns are short and thirteen-jointed 

 in the males, twelve-jointed in the females ; the body is rather long, 

 forming a club, being slender at the base, and the edges of four 

 of the segments are hoary; the four wings are dusky at then- 

 extremities ; and the brown nervures form six distinct cells in the 

 superior : it varies in size from | to J an inch in length, and the 

 wings expand from 5 to 8 lines, or nearly £ths of an inch. 



These insects are abundant upon old posts, palings, or out- 

 houses, gates, barns, stable-doors, &c., in which they form 

 burrows to deposit their eggs, from the middle of May to the end 

 of summer : it appears that they collect masses of aphides, pro- 

 bably to feed their young, which also subsist upon dead spiders, 

 carried into the nests by the parent flies. 



14. Pemphredon unicolor, Fah'"- Black, shining, clothed 

 with greyish hairs ; head large, nose silvery ; horns short, curved, 

 thirteen-jointed in the males, twelve -jointed in the females; head 

 and thorax punctured ; body oval, pointed and attached to the 

 trunk by a narrow neck; wings, four; iridescent but smoky, 

 superior with eleven cells, formed by blackish nervures ; length 

 J of an inch; expanse 5 lines. 



This, as well as a larger species, called Pemphredon luguhris 

 of Fabricius, may be seen during the summer months, carryirig 

 immense quantities of aphides into straws in thatch, and holes in 

 wood, posts, &c., to feed their young maggots upon. The follow- 

 ing species, and likewise an allied one, have similar habits. f 



15. Diodontus gracilis, Curtis.X Smaller and more slender 

 than Pemphredon, to which it is nearly related, but is distinguished 

 by its notched upper lip : it is black and shining ; the head and 

 thorax are punctured ; lower part of face clothed with silvery hau'S 

 in the males; the four feelers and a stripe outside of the jaws 

 yellowish-white ; the body is elliptical and pointed, attached to 

 the thorax by a short neck; wings transparent; nervures and 

 stigma pitchy ; tips of thighs, base and tips of shanks and the feet 

 ochraceous, excepting the hinder pair ; length i of an inch ; 

 expanse 4 lines. 



16. Psen atratus, Panz:^ black, shining ; antennae thirteen- 

 jointed, curved in the female, rusty beneath, especially in the 

 males ; face silvery with hairs ; head and thorax finely punctured ; 

 body ovate, conical at the apex, attached by a short slender neck 

 at the base ; wings four, transparent, beautifully iridescent, the 



* Curt. Brit. Ent., pi. and fol. 632, and Kennedy in Lond. and Edinb. 

 Phil. Mag., Jan. 1837, p. 18. 



f Diodontus corniger, Shuck., and Phil. Mag., January, 1837, p. 17. 



% Curt. Brit. Ent., pi. and fol. 496, Guide Gen., 685\ 5. 



§ Curt. Brit. Ent., second edition, fol. and pi. 25, Guide Gen. 691, 2. 



