126 TURNIP. 
Turnip-seed Weevil, Ceutorhynchus assimilis, Payk. 
Turnip and Cabbage Gnat Midge, Cecidomyia brassice, Winn. 
CEUTORHYNCHUS ASSIMILIS.—I1 and 2, beetle; 3.and 4, maggot; 7 and 8, pupa 
(all natural size and magnified) ; 5, infested Turnip pod. 
Tue following paper is inserted not so much with a view of entering 
on the life-history of the Turnip-seed Weevil, which has already been 
given, but to draw attention to some very special points of difference 
in the methods of the attack of the maggots of this weevil to the seed 
of Turnips and Swedes; and those of the maggots of the Turnip and 
Cabbage ‘‘Gnat Midge,”’ the Cecidomyia brassice, which, from com- 
parison of observations previously sent with samples of attack 
forwarded to me during the past two years, I conjecture at least to 
share the damage to unripe seed in the pods with the Turnip-seed 
Weevil more than is generally known of. 
Taking the habits of the Gnat Midge grubs first, these are found 
towards the end of May and in June in the seed-pods of Turnip or 
other plants of allied kinds in great numbers, where they suck the 
juices from the seeds. These infested pods do not ripen properly ; 
they swell at the attacked spots, become prematurely yellow, and split 
open, so that the mature maggots fall out and bury themselves to turn 
to chrysalis state in the ground. The little gnat-like flies, which are 
not as much as one-twelfth of an inch in length (1:25 mm.), appear 
in about ten days, and presumably start a new generation. 
The method of attack of the maggots is similarly described by 
Dr. J. Ritzema Bos* in the following words :—‘‘ They suck out the 
juice of the unripe seed, which is thus destroyed before the time for 
maturity is arrived. The pods swell at the maggot-infested spots; 
they ripen and wither sooner than those that are healthy, and burst, 
and the larve fall to the ground, where they pupate. In about ten 
days swarms of little gnats make their appearance. These certainly 
* ¢Tierische Schidlinge und Niitzlinge,’ von Dr. J. Ritzema Bos. Berlin, 1891, 
p. 588. 
