82 



Fruit moths caused little damage iu 1919, though this is contrary 

 to the experience of 1920. A few indi\-iduals of Ofhreis {Ophidercs) 

 fullonica were observed towards the end of 1919, and Achaea obvia 

 appeared in swarms from mid-March and attacked all maturing fruit. 

 No study has yet been made of the bionomics of these pests, and their 

 food-plants are not yet known. They are stated to migrate to higher 

 elevations with the ad\ent of the dry season. 



Cotton grown from seed imported from Jamaica was severely 

 attacked by a leaf-blister mite, possibly Eriophyes s^ossypii, Banks. 



Byaks (L. p.). The Nematode Disease of Wheat caused by TvlencJms 



(ritici.—U.S. Dept. Agric, Washington, D.C., Bull. 842, 7th 



September 1920, 40 pp.. 6 plates, 6 figs. 'Received 21st December 



1920.] 



The bulk of this information dealing with the Nematode, Tylenclius 



tritici, Steinb., its distribution, spread and control has been noticed 



elsewhere [R.A.E., A, vii, 324, 380]. Although primarily a parasite 



of wheat, this pest may apparently also attack rye, oats, emmer 



[Triticiim] and barley. 



As a result of experiments to ascertain the effect of various chemicals 

 on this Nematode, it is evident that it is strikingly resistant to their 

 action, and that substances not injurious to wheat fail to kill the larvae. 

 The Nematodes may, however, be destroyed by submersion in water 

 for 10 minutes at a temperature of 51° to 52° C. [124°-126° F.], but 

 if the galls are not first removed the temperature should be raised to 

 54° or 56° C. [129°-133° F.], and the wheat submerged for 10 to 12 

 minutes. 



Back (E. A.). Insect Control in Flour Mills.— t^.S. Dept. Agric, 

 Washington, D.C., Bull. 872, 11th November 1920, 40 pp., 15 figs. 



Insect pests in flour and cereal mills are responsible for great losses, 

 but the obvious advantages of preventive measures and the modern 

 improvements in mill construction are gradually bringing about a 

 decrease in them. The insect that most seriously affects milling opera- 

 tions is Ephestia kilhniella (Mediterranean flour moth), which is now 

 established in almost ever\^ mill in America and, owing to the webbing 

 habit of the larvae, sometimes completely stops the machinery. Under 

 ordinary conditions in flour mills about nine weeks are required to 

 complete the life-cycle, though this varies greatly with the temperature. 

 Below 55° F. activity is suspended. The usual method of entry into 

 mills is in sacks that have been used before, or when second-hand 

 machinery that has not been properly fumigated is installed. Mills 

 in any infested centre are liable to infestation in spite of all precautions, 

 as the moths can fly from building to building. The need for cleanliness 

 cannot, however, be over-emphasised. The insects prefer to oviposit 

 and develop in flour and cereals lying in undisturbed, darkened 

 situations. The proper construction of a good type of mill, the liberal 

 use of air-slaked lime, and the care of sacks and bags are discussed. 



Some check on the numbers of E. kilhniella is exercised by the 

 parasites, Habrobracon hebetor, Say, and Omorga frnmentaria, Rond., 

 but these can only be considered an accessory factor in control. The 

 two artificial remedies that have proved of the greatest value are 

 fumigation with hydrocyanic acid and super-heating. The fumigation 

 method is described, and all directions for the process are explained. 

 While this is effecti\c against E. kilhniella, it is not so satisfactory^ 

 against some of the stages of Tribolimn confusum, Duv., and T. 



