524 Scientific Proceedings, Royal Dublin Society. 



to later. This segment carries at each side of the median line one long and 

 thi'ee short bristles dorsally, two long bristles laterally, while two further 

 bristles project between the anal hooks (PI. XIX, fig. 42). 



The tenth segment is very small, and is situated ventrally to the ninth, 

 by which it is completely obscured in dorsal view. 



The spiracles open in the pleural region of the metathorax and abdominal 

 segments one to five; no spiracles can be seen on abdominal segments six to 

 ten. A very short bristle occurs to the inner side of each spiraeular open- 

 ing, and similar bristles are present and occupy corresponding positions on the 

 segments devoid of spiracles. The abdominal sternites are not armed, and 

 as the pupa normally lies on its back in the cocoon, the projecting spines of 

 the tergites serve to support the body, and prevent the possibility of damage 

 from excessive moisture. 



Unlike the pupae of some other Chrysomelidae, the males and females of 

 this species do not differ in size. The chief external difference in the sexes is 

 seen in the region of the two posterior abdominal segments. In the female 

 these have, projecting from the ventral surface, two fleshy, finger-like structures, 

 one at each side of the median line, and just anterior to the minute tenth 

 segment (PI. XIX^ figs. 41 and 45). They serve to accommodate the palps of 

 the ovipositor ; and these organs can be seen during the later days of pupal 

 life protruding into their pouch-like sheaths in suitably cleared specimens. 

 In the male pupae no such projections exist ; instead there is a single median 

 enlargement, which presumably accommodates the aedeagus of the adult 

 (PI. XIX, figs. 43 and 44). 



11. — Details of the Life-histoey. 



In common with the other species of flea-beetles whose life-histories 

 have been studied, Longitarsus parvulus spends the winter in hibernation in 

 the adult state. Observations in Co. Derry go to show that the beetles 

 issue from their winter quarters in spring, as soon as the weather becomes 

 favourable — usually some time in April — and go in search of food prior to 

 the commencement of reproductive activities. Early in May they migrate 

 to fields of flax seedlings, and the females deposit their eggs in the soil from 

 the middle of May onwards, according to the prevailing weather. Egg-laying 

 may continue for about six weeks. In 1921 larvae were found from the 1st 

 of June until late July, and pupae from the end of June until the middle of 

 August. Emergence of the adults continued during the last weeks of July 

 and throughout the first weeks of August. The maximum emergence of 

 adults in 1920 was during the last week of August and the first days of 

 September, but in 1921 a maximum was reached about the 25th July. 



