230 



hatched, after which a moult takes place as a rale every two days. 

 The total life-history from egg to adult occupies between 15 and 17 

 days. Thus at least two generations may occur on one crop, since all 

 ears do not ripen at the same time. A disease, the symptoms of which 

 resemble " pebrine " in silk -worms, is the only natural check known. 

 A bacterium was isolated from infected individuals and grown, but 

 the experiments made to prove whether it was the agent or not were 

 inconclusive. If a dead insect were left in a breeding jar with a 

 healthy one, the latter in the course of two or three days almost in- 

 variably contracted the disease and died. The best method of artificial 

 control so far suggested consists of shaking the ear over a tin or pan 

 containing water with a film of kerosene on it. This can however only 

 be done while the stems are young and sappy. Spraying is out of 

 the question, and experiments with light traps proved useless. 



Preventive Treatment of Thrips. — Agric. Gaz. Neiv South Wales, 

 Sydney, xxvii, no. 2, February 1916, p. 126. [Received 

 1st April 1916.] 



An outbreak of thrips occurred during 1915 in orchards in the Mount 

 Barker district of West Australia. The following preventive measures 

 were suggested : — (1) The destruction by ploughing in or burning of all 

 grass and weeds in or at the edges of orchards ; (2) the application of 

 Hme-sulphur or red oil emulsion just before the buds burst ; (3) 

 a tobacco and soap wash spray when thrips are observed on opening 

 flower and leaf buds. 



Hughes (F.). Fumigation of Cotton Seed by Gaseous Hydrocyanic 

 Acid.— Agric. Jl. Egypt, Cairo, v (1915), nos. 1-2, 1916, pp. 84-90. 



This report is pubHshed in view of the possibiUty of the vacuum 

 process for treating cotton seed by hydrocyanic acid being employed 

 in Egypt against the pink boll worm {Gelechia gossypiella) and other 

 insect pests. The following conclusions were arrived at : — (1) Although 

 minute quantities of hydrocyanic acid have been found in all samples 

 of treated seed examined, the amount is so small that no fear need be 

 entertained as to its proving in any way toxic. The acid appears to 

 be for the most part expelled or destroyed in the process preparatory 

 to the extraction of the oil. (2) The quantity of hydrocyanic acid 

 found in the cake prepared from treated seed is so small that it would 

 in no way interfere with its use as cattle food. (3) No hydrocyanic 

 acid could be detected in the partly refined oil. No alteration in its 

 character or properties could be detected. (4) The considerable 

 absorption of hydrocyanic acid gas by cotton seed appears to be very 

 largely due to the solubility of the gas in the oil contained in the seed. 



Storey (Gr. A.). Notes on Large Scale Experiments against the Pinli 

 Boll Worm in Cotton Seed. [Agric. Jl. Egy2)t, iv, no. 2 (1914) 

 1915.]— ^^nc. Jl. Egypt, Cairo, v (1915), nos. 1-2, 1916, p. 91. 



A note by M. Crovdsier on the construction of a full -sized hot air 

 machine for killing pink boll-worms {Gelechia gossypiella) in cotton 

 seed, which was omitted from a former paper [see this Review, Ser. A, 



