The glucosinolate content of the 3 host plants, viz. yellow sarson, Brassica campestris L. var. yellow sarson, Chinese cabbage, Brassica campestris L. var. pekinensis and taramira, Eruca sativa Lam. var. ITSA differed qualitatively as well as quantitatively mainly with respect to allyl-, methylthiobutyl-, pcnt-d-enyl-, methyl-and benzylglucosinolates. The mean number of total probes on feeding media incorporated with crude extracts containing glucosinolates from 0,25, 0·50 and 1·0 g green parts of taramira per ml of feeding media was 5,8, 6·7 and 8·4, respectively. Such probes in case of yellow sarson and Chinese cabbage were 2,6, 2·2 and 1'5; and 2'6, 2·0 and 3'0, respectively. The mean number of probes on feeding media containing sinigrin (K + -allylglucosinolate) at the rate of 0,125, 0'25, 0·50 and 1'0% was 1,9, 3-3, 3-9 and 5'2, respectively. Uptake of feeding media incorporated with extracts containing glucosinolates from taramira, yellow sarson and Chinese cabbage varied from 4'05-9'40, 31,5-52,0 and 30'5-51'3%, respectively. Similarly, the uptake in the case of feeding media containing sinigrin (0'125-1~~) varied from 1·6-44·95%.Two of the 3 crucifers selected for the present studies, yellow sarson, Brassica campestris L. var. yellow sarson; Chinese cabbage, B. campestris L. var. pekinensis are susceptible and third, taramira, Eruca sativa Lam. var. ITS A, is resistant to the attack of mustard aphid, Lipaphis erysimi (Kalt.). For the purpose of extraction and analysis 695