83 



castaneiim, Hbst. {ferrugineiim , F.) (flour beetles), Laemophloeus 

 minutns, 01. (bran beetle), Tenebroides mauritaniciis, L. (cadelle) and 

 Silvaniis sitrinamensis, L. (saw-toothed grain beetle). These beetles 

 are naturalh^ more resistant to the effect of gas, as they secrete them- 

 seh'es in tlic cracks and crevices of wooden elevators, etc., where the\' 

 are inaccessible to it. For these the most practical remedy is the 

 application of a high temperature, which at the same time destroys all 

 other mill-infesting insects. Heat should be applied in the summer, 

 a temperature of 118° to 125° F. in all parts of the mill being necessar\^ 

 to kill all pests. A pressure of 25 to 50 lb. steam heat is recommended 

 for the purpose. Directions for carry'ing out this process are 

 given. It is estimated that in mills of moderate size the heat method 

 saves sufticient to pay in five years for the cost of its installation. 

 Neither this nor the fumigation method injures the building or plant 

 or affects the baking qualities of flour. 



Entomology. — 45th Ann. Rept. Ontario Agric. Coll. & Exp. Farm, 1919, 

 Toronto, 1920, pp. 31-34. [Received 21st December 1920.] 



The transformation from winter to summer conditions in Ontario in 

 1919 was unusually rapid, and insects appeared in large numbers with 

 startling suddenness. Aphids were very destructive to many crops. 

 Hell at his obsoleta (corn ear worm) caused much loss to maize growers 

 in south-western Ontario. This is a difficult pest to deal with, and the 

 only practicable remedy is to plough the infested fields as late as 

 possible in the autumn in order to expose the pupae to the cold. Anv 

 ears found to be infested should be cut off and used as pig food. In 

 Ontario, H. obsoleta also occasionally attacks tomato fruits and the 

 buds of tobacco. Alabama argillacea (cotton moth) was observed in 

 several localities in September, having migrated northward from the 

 cotton fields over a thousand miles away. It did not, however, do any 

 damage. Weevils in stored grain are increasing in number and 

 destructiveness. Only perfectly clean receptacles should be used for 

 storing grain, and no refuse should be allowed to accumulate in the 

 store-houses ; frequent examination of bins and bags should be made, 

 and no grain should be left undisturbed for more than a year. 



The usual infestations of fruit pests occurred, none of them being of 

 outstanding importance. Of vegetable pests, Phorbia [Chortophila) 

 brassicae (cabbage maggot) has been the subject of many tests, and of 

 the various substances tried, corrosive sublimate gave the best results. 

 In the case of radishes after two treatments 90 per cent, were free from 

 infestation, and they were also larger and of better quality. For 

 Pieris rapae dusting with calcium arsenate and hydrated lime, and 

 spraying with tobacco extract, both proved disappointing. Treatments 

 that proved satisfactory^ were pyrethrum powder 1 oz. to 2 gals, of 

 water, sprayed directly into the heads of the plants ; or a diy mixture 

 of about 1 oz. of Paris green to 1 gal. of middlings. This last remedy 

 is applied by taking a small quantity and scattering it between the 

 fingers where the caterpillars are feeding in the heads of cabbages. 

 This method would not be safe on cauliflowers. For Thrips tabaci 

 (onion thrips) 1 part of Blackleaf 40 to 400 parts of water, with 1 oz. 

 of common soap to 2 gals, of the liquid, was found effective. 



Pests of bush fruits that received attention during the }'ear included 

 Pteronus ribesii (currant sawfly), which confined its attacks to red and 

 white currants and gooseberries ; Aegeria [Sesia) tipiiliformis (imported 

 currant borer) ; and Metallns bethunei (blackberr\' leaf-miner), wliich is 

 becoming increasingly abundant in many districts. 



