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TURNIP. 



Turnip-seed Weevil. Ceutnrhjpichus assimilis, Payk. 

 Turnip and Cabbage Gnat Midge. Cecidomyia brassicce, Winn. 



'^' 



Cedtorhynchus assimilis. — 1 and 2, beetle ; 3 and 4, maggot ; 7 and 8, pupa 

 (all natural size and magnified) ; 5, infested Turnip pod. 



The causes of loss to Turnip -seed growers from attacks to seed, 

 accompanied by distorted growth and premature yellowing and crack- 

 ing open of the pods, have for many years been the subject of inquiry. 

 The damage is referable to two quite distinct kinds of infestation, one 

 being that of the Turnip-seed Weevil, figured above ; the other of the 

 Turnip and Cabbage Gnat Midge, Cecidomyia brassicce. 



The Seed Weevil has been repeatedly mentioned before, especially 

 in 1891, but is just referred to again in order to point out the diifer- 

 ences between it and the " Gnat Midge," and their respective methods 

 of attack to the seed. The little beetle is not quite the sixth of an 

 inch in length, including its (comparatively) long and curved proboscis. 

 When freshly developed, it appears to be grey, owing to the coating of 

 grey or whitish hairs with which it is covered ; but when these are 

 rubbed off, it is black. There are two broods in the year, of which the 

 second lives through the winter, and the beetles, which have great 

 power of dispersing themselves, from the ample size of their wings, 

 feed on flowering shoots of Turnip, Eape, Mustard, or allied plants. 

 The maggots feed on the seed within the pods, and by a little careful 

 watching may be seen in the act of preying on the seed with their little 

 brown jaws, and the seed in various stages of consumption, from a 

 small piece having been eaten to the whole of the seed being cleared 

 out of the skin by the maggot still within, and wet green rejectamenta, 

 the result of feeding, lying at the caudal extremity of the maggot shows 

 that the devouring of the seed is then going on. 



This method of feeding, that is, the consumption of the substance of 

 the seed, is an easy way of distinguishing the attacks of the weevil 

 maggots from those of the maggots of the Gnat Midge, which do not 

 eat up the seed, but destroy it by suction, so as to cause the seeds to 

 shrink and sink in. 



