499 



30 to 40 per cent, of the eggs are thus destroyed. The Tachinid 

 larva requires 19-22 days to attain maturity. This slow development 

 is due to the fact that P. segregata does not find in the small body 

 of the host caterpillar a store of food sufficient for. rapid growth. 

 The Tachinid larva pupates 12-16 hours after emerging from its host. 

 The infested caterpillar shows a decided tendency to pupate and 

 seeks a suitable shelter for the purpose, so that the parasitic larvae 

 in the last days of their development are protected against unfavourable 

 conditions and natural enemies to the same extent as if in a host 

 pupa. Caterpillars in which eggs have been laid early in the season 

 seek a pupal shelter early but are unable to pupate, while those in 

 which eggs have been deposited much later become apparently normal 

 pupae, but at an earUer date than if they were uninfested. It is 

 therefore a mistake to destroy the caterpillars that are ready to pupate 

 early in the season on the lower parts of trees. 



Prell (H.). Zur Biologie der Nonnentachine. [Notes on the Biology 

 of the Nun Moth Tachinid.] — Vereinsschr. Forst-, Jagd- u. Natur- 

 kunde, Prague, 1916-17, no. 3-4, pp. 168-178. [Received 9th 

 September 1919.] 



This paper contains further details on Parasetigena segregata and 

 discusses the difEerences between the author's observations and those 

 of Loos [see preceding paper] ; such difEerences may be due to varia- 

 tion in the value attached to the temperature factor. 



Loos (K.). Xyleborus saxeseni, Ratz. — Vereinsschr. Forst-, Jagd- u. 

 NaturJcunde, Prague, 1917-1918, no. 10-12, pp. 372-377, 6 figs. 

 [Received 9th September 1919.] 



This article describes the mines of Xyleborus xylographus, Say 

 {saxeseni, Ratz.), which — as^^found in an apple tree — ^present many differ- 

 ences from EichofE's description of them. 



SiAHAjA (E. L.). HelopeUis-BestTi]dmg op de Onderneming Leuwi- 

 manggoe. [Anti-Helopeltis Work on the Leuwimanggoe Estate.] 

 — Meded. Proefstation voor Thee, Buitenzorg, Ixiv, 1919, pp. 4-9. 

 [Received 12th September 1919.] 



From July to December 1918 experiments were made in capturing 

 Helopelfis on an area of 88 acres in order to ascertain the extent 

 to which infestation could be checked at a cost of 35s. per acre, 

 this figure being based on the average price and average yield of leaf, 

 and being one that would be remunerative and become more so as 

 the price of tea increased. Both the direct and indirect loss due 

 to Helopeltis was calculated. The average cost per acre per month 

 was 4s. 3d., and it should be noted that the six months chosen were 

 those in which Helopeltis is most dangerous. On the 40 acres in which 

 pruning was done earhest, the danger period was over by the end 

 of December, in which month the cost was 3s. per acre, while 

 on the remaining area the December cost was 6s. Id. per acre 



