108 



Queries and A?is'wers. 



the outskirts of London, attracted, no doubt, by the cabbages and other 

 vegetables exposed for sale. — W. T. B. Dover, August 18. 1831. 



P.S, Mifchamy Surrey, Oct. 10. Subsequent observation induces me to 

 believe that I have by no means over-rated the ravages of the Microgaster 



(^g. 40.); but that what is stated 

 above, may be considered as no more 

 than an average example of its de- 

 structive powers. The chalk cliffs 

 at Dover abound with the wild cab- 

 bage (jBrassica oleracea), which, as 

 might be expected, aflbrds food to 

 an immense number of the cabbage 

 caterpillars ; and, accordingly, the 

 butterfly is exceedingly abundant in 

 that neighbourhood. The latter end 

 of September I saw many of the cater- 

 pillars creeping about the cliffs, and 

 undergoing their transformation ; and 

 I remarked that those which were 

 infected by the Microgaster, far ex- 

 ceeded in number those which would 

 arrive at the chrysalis state. I have 

 also had occasion to make the same 

 remark in the place from which I 

 date this postscript. I may add, that 

 on the 25th of September, I observed 

 at Dover many specimens of Micro- 

 gaster in the winged state, adhering 

 . c^-u , , . . ^ >n i to the puna, from which they ap- 



o, Larva of the natural size^: 6, magnified. i f i • i ^i 



c. Imago of the natural size; rf, magnified. peared to have just emerged J and 



e, Perfect insect, natural size ;/, magnified. the Same also at Mitcham on the 



^, Cocoon, natural size; A, magnified. £.,, c r\ ^ i rr\ n- ^u 



i. Cluster of cocoons around the larva of V(m. oth ot October. 1 he tlies thuS pro- 



tia brassicag. duced at this late season of the year, 



would, no doubt, attack the later broods of cabbage caterpillars ; which 

 are often to be met with so late as the end of October, or even in Novem- 

 ber. The large and continuous supply of this little parasite throughout 

 the summer and autumn, i. e. so long as its services are required, is one of 

 those wise and beneficent provisions, which cannot but excite our admir- 

 ation.— W^. T,B. 



An additional instance of the check to superabundant increase effected 

 on a species of Trichiosoma by one of the /chneumonidae, is given in the 

 present Number, p. 



On January 1. 1831. I took a cluster of minute, dirty, pale-yellow co- 

 coons off the face of Kensington Garden wall, and enclosed it in paper. 

 On opening this paper, in the close of the summer of 1831, almost or 

 quite every cocoon had yielded a Microgaster glomeratus, and the little 

 flies were all dead in the paper. The lids of the cocoons were quite ob- 

 vious, as shown in the appended figure {Jig. 40. h) ; some detached, 

 others hinged. In the end of September, or early in October, 1831, 

 along the last IrV furlong of Kensington Garden v/all (beside the Bays- 

 water road), I witnessed nearly a dozen caterpillars of Pontia brassicge 

 which had just yielded, or were then yielding, both their lives and large 

 clusters of cocoons of Microgaster glomeratus. These cocoons were 

 then especially conspicuous, from their bright rich yellow hue ,• but with 

 the dirt of the road, and the filth, which the rain washed off the wall's face, 

 upon and over them, were, in a fortnight or about, so obscured as to 

 obfige me to search to find a cluster. On finding a cluster, I was a 

 little surprised to observe two or three cocoons empty, and to notice a 



