Observations on Insects affecting the Turn/p Crojos. 69 



found that many of them were empty, but in two or three I de- 

 tected maggots by holding the leaf up to the light (fig. 27) ; they 

 were of a pale green colour, the mouth being armed with two 

 little horny-hooks ; one changed to a pupa (fig. 28) inside of the 

 blister the same day, and another I found dead shortly after at 

 the bottom of the tin-box in which they were placed, and in a day 

 or two I saw another pale greenish maggot in a box with a blis- 

 tered leaf, which soon buried itself under the cuticle, and changed 

 to a pupa of a chestnut colour, with two divaricating horns on 

 the head (fig. 29), and on the 4th of August I bred from it a fly 

 (fig. 30), which agrees pretty well with Fallen's description of 



23. Drosophila flava : it is ochraceous, sparingly covered with 

 black bristles, the face is silky white, eyes black, and the lobes at 

 the apex of the abdomen are black ; the seta or bristle of the 

 horns is likewise black and only feathered above, and there is a 

 slate-coloured spot on the crown where the three little eyes are 

 placed: down the centre of the thorax is a light rusty line^ with 

 the indication of one on each side ; the legs are very pale ochreous; 

 the wings are yellowish but iridescent, and the nervures are pale- 

 brown : length 1 line, expanse 2 J. 



In October numbers of the leaves amongst the Swedish turnips 

 likewise exhibited pale patches, which were almost white, or the 

 colour of parchment above, but, as usual, no indications of their 

 being infested were visible beneath. In these blisters I found 

 sometimes as many as three maggots, which I presume were the 

 offspring of a second brood : they shortly became brown pupae at 

 the bottom of the box, from which I am induced to infer that they 

 often come out of the blisters when arrived at maturity, and 

 enter the earth to undergo their transformation to the chrysalis 

 state. From some of the earlier pupae I obtained two little 

 parasitic hymenopterous flies : one appears to be the Ceraphron 

 niger''' of my cabinet; and the other is, I believe, Miscogaster 

 virldis of Walker. f 



The other fly called Piiytomyza, is bred from the under-sides 

 of the turnip- leaves, where the maggots form long irregular 

 galleries (fig. 31) inside of the lower cuticle, and these miners 

 are not visible on the upper-side of the leaf One of the maggots 

 changed the third week in July to a dark-brown pupa (fig. 32) 

 beneath the epidermis, and it v^as furnished with two small horns 

 at one end : on the 28th a fly came forth, which was the 



24. Piiytomyza nigricornis of Macquart (fig. 33) : it was slate- 

 black ; the head and thorax were sprinkled with a few black 

 bristles ; the horns are brown, with a naked bristle ; the head is 

 pale ochraceous, excepting a spot on the crown; the tips of the 



* Curt. Guide Genus 581 b, 41. t Ibid. Gen. 638, 17. 



