and lasts for owr 2 weeks. TIr- niaxinuiin ck'i)Osition occurs bctwvcn 

 the 7tli and 11th days. Both in August and in January (at room 

 temperature) incubation lasts 8-10 days. Parthenogenetic reproduction 

 does not take place. The young larvae at once begin feeding and 

 prepare tube-like webs from the fibres or hairs of the material at their 

 disposal. When the larvae moult they construct oval-shaped cocoons, 

 somewhat pointed towards the ends. The larvae are not confined to 

 their food-substances for the material for their cocoons ; paper, glass- 

 wool, their own excreta, etc., may be used. The number of moults 

 varies, with an observed maximum of 11. On an average the first 

 moult occurs 9-10 days after hatching, the second after an interval of 

 12-13 days, the third after an interval of 15-20 days. An average 

 interval of 25 days separates the further moults. The larval stage 

 varies in duration according to the number of moults. Feeding tests 

 confirm Frickhinger's observations that cotton, linen and silk are 

 either rejected or unwilUngly accepted, and the resultant moths were 

 only half the size of those from larvae fed on wool. Larvae that are 

 kept from feeding withdraw into their cocoons, pass through a resting 

 stage, pupate and yield adults able to deposit fertile eggs. Food was 

 withheld from 3-wec^k-old larvae for 8i months ; some died, but the 

 others, on being fed, developed in a normal manner. 



Pupation takes place in the above-mentioned cocoons, tins stage 

 usually lasting 18 or 19 daj^s. 



The adults mate on emerging, and have an average life of 30 days. 

 There are two chief flight periods, in spring and in autumn, but they 

 are not sharply differentiated owing to the prolonged larval stage. 

 In general it may be said that the period from egg to egg extends from 

 5| to 8| months. For this reason all stages are present throughout 

 the year. 



Most preparations used against this moth hitherto have been 

 repellents such as camphor, naphthahne, etc., designed for impregnating 

 the various cloths, but as they cannot entirely prevent oviposition 

 and do not kill the larvae already present, they are useless to check 

 the pest. Neither repellents nor substances effective against onl}^ one 

 of the stages are satisfactory. Fumigation with hydrocyanic acid gas 

 solves the problem. A number of experiments were made to ascertain 

 the requisite strengths, and the results are given in tabular form. 

 As Andres had previously observed, the larvae are the most resistant, 

 but they succumb in 2 hours to 1 volume of gas per cent., in 4 hours 

 to 0-5 volume per cent., or in 16 hours to 0-2 volume per cent. These 

 figures also apply to the pupae. The eggs are destroyed by an exposure 

 of 1 hour to 0-25 volume per cent., and the same lack of resistance is 

 shown by the adults, the figures representing actual and not calculated 

 strengths. In practice either the strength or the time must be doubled, 

 as it will not be possible to maintain unimpaired a strength of 1 per 

 cent, during a period of 2 hours. 



Stellwaag (F.). Arsenmittel gegen Wein — und Obstbauschadlinge. 



[Arsenic Preparations against Pests of \'ines and Fruit Tiees.J — 

 Zcitschr. angeio. Entom., Berlin, vii, no. 1, September 1920, 

 pp. 172-180. 



Paris green and Urania green are the two best-known arsenical 

 insecticides. Though manufactured in Germany, it is only of quite 

 recent years that tlieir use has been permitted there. In 1917 the 



