A. REIJNE, A COCOONSPINNING THRIPS. 43 



at the emergence of the adult, either mechanically or b\' the 

 secretion of a fluid, was not traced. Perhaps the peculiar 

 hook-like appendage, found only on the fore-legs of the family 

 Aeolothripidae, and which is also present in F. temiicornis 

 (fig. 6), may help in breaking the cocoon. 



As the cocoon is rather opaque, it is somewhat difficult 

 to observe the development of the larva. In one case the 

 cocoon was very thin, so that the transformations could be 

 easil}' traced ; the}' were still better seen when the larva 

 pupated free, as twice happened, but then the development 

 seems to be an abnormal one. In eight observations the 

 following progress of development was found. 



About 24 hours after the spinning had begun, a pupa 

 was present. On the 2""^ day the tip of wingcases reached 

 the 2""^ segment of the red abdominal band ; the pigmentation 

 was still the same. On the 3''^ da}' the length of the wingcases 

 was the same. The white segments of the abdomen behind 

 the red band had turned slight reddish. Head and thorax 

 were orange, the eyes had become darker. On the 4'^ day: 

 Wingcases extending to the end of the red band, antennae 

 to the last [G^) segment of it. On the 5'^ day the whole 

 abdomen, except its tip, was red, while on the G^ da}' the 

 first 3 abdominal segments had acquired a white colour as 

 in the adult (fig. 3). The wingcases had distinct setae, those at 

 the tip of abdomen were also present. Antennae still recurved. 

 On the 7'^ day the antennae were detached from the bod}-, 

 so that the adult probably had emerged ^). Wingcases the 

 same. On the 8'^ da}^ the whole body, with exception of 

 the first 3 abdominal segments, base of antennae and last 

 segment of abdomen, had a dark colour; the wings showed 

 distinct veins and dark crossbands. On the Q'*" da}' the adult 

 left its cocoon "(in one case on the 10'^ da}"). 



In the two experiments where no cocoon was spun, the 

 development seemed to be abnormal and defective : 



i) On the first da}' the larva that had begun to spin 

 (fig. 4) left its silk when it was disturbed, second da}' : 



1) Another, released from its cocoon at the 7'h day, had all the 

 characteristics of the adult, but the pigmentation was still very imperfect. 



