34 



factor. Clothes are rendered safe by immersion in a 2 per cent, 

 solution of lysol for 30 minutes at a temperature of from 100° to 

 104° F., whatever the subsequent treatment may be. Cold solutions 

 were effective when used at a minimum strength of 1| per cent, with 

 an immersion period of 1 hour, provided that the solution remaining 

 on the fabric after dipping was allowed to dry in. Sponging infested 

 hair with a 2 per cent, solution of lysol warm or cold is useless if 

 this is followed immediately by rinsing. This is thought to be due 

 to a reflex action in the louse by which it closes the spiracles for a 

 short period, thus preventing penetration of the noxious fluid. 

 Experiments were also made by placing lice and eggs on flannel 

 which was subsequently immersed for 5 minutes in kerosene at a 

 temperature of 68° F., with the result that all active lice died within 

 48 hours regardless of subsequent treatment. The death of active 

 lice following immersion in kerosene appears to be due rather to the 

 oil on the surface of the insect or the object to which it clings obtaining 

 entrance to its body after removal from the fluid than during the 

 short period of immersion. As regards the eggs, penetration by 

 kerosene is too slow for its entrance to occur within the time of 

 immersion, but subsequent to their removal the fluid or its vapour 

 inhibits development. In experiments where the eggs immersed in 

 kerosene hatched the young lice died in the process of emergence 

 from the egg. 



Cattle-Tick Regulations. — N. Z. Jl. Agric, Wellington, xix, no. 4, 

 20th October 1919, p. 263. 



The laws that came into force on 2nd October 1919 concerning 

 quarantine, notification and treatment by dipping or some other 

 effective method of dealing with tick-infested cattle, are reviewed. 

 For the purpose of these regulations cattle-tick means any parasite 

 of the family Ixodidae and does not include the Hippoboscid fly, 

 Melophagus ovinus. All stock intended for removal must be treated 

 as authorised by the inspector, forty -eight hours previously. 



Rich (S. G.). Are the Odonata of Economic Value ? — S. African 

 Jl. Sci., Cape Town, xv, no. 8, July 1919, pp. 611-612. 



In Africa adult dragonflies are apparently not of much economic 

 importance, but in the nymphal stage they are probably both beneficial 

 and harmful. In several rivers and pools examined where dragon- 

 fly nymphs were abundant very few mosquito larvae were found, 

 although conditions seemed ideal for them. In districts where 

 mosquitos were abundant there were very few dragon-flies to be seen. 

 With one exception all waters containing nymphs of Odonata were 

 sparsely inhabited by fish. 



Storey (G.). Keys for the Determination of Egyptian Mosquitos 

 and their Larvae. — Bull. Soc. Entom. Egijpte, Cairo, 1918, no. 4, 

 September-December 1918, 1919, pp. 84-106, 2 plates. [Received 

 29th December 1919]. 



Keys are given for the determination of adult mosquitos of Egypt 

 from easily visible external characters ; for the determination of the 



