REPORT OF THE ENTOMOLOGIST 221 



SESSIONAL PAPER No. 16 



female is very heavily bodied, she does not fly but deposits the eggs to the number of 

 about five hundred in the characteristic felt-like masses. 



The young caterpillars are destroyed by spraying the trees with an arsenical 

 poison; lead arsenate is the usual poison employed. When the larvae are older they 

 are more difficult to kill; advantage is taken of the fact that they descend the trees 

 in the early morning to shelter during the day. On ascending the trees they are 

 caught either by means of a strip of folded burlap or a band of ' tanglefoot ' or other 

 sticky substance around the tree. Probably the most effective method of destroying this 

 pest is the destruction of the egg masses, which can be accomplished any time from 

 the end of August to the middle of April. They are easily seen and usually accessible 

 and are destroyed by the application of a dab of creosote. This can be done by means 

 of a small stiff-bristled brush. 



Most careful watch should be kept for this species and any suspected insects should 

 be immediately mailed to the Division of Entomology for identification. Those 

 regions which are specially liable to become infested with the Gipsy Moth are the 

 regions already infested with the Brown- tail Moth, namely, those parts of New Bruns- 

 wick, adjoining the State of Maine and the maritime regions of Nova Scotia, especially 

 where there is any communication with the ports of Massachusetts and southern 

 Maine. 



FUMIGATION WITH HYDBOCYANIC ACID GAS. 



During the year a number of cases have occurred where buildings such as houses, 

 warehouses and mills required fumigation for insects. When general infestations of 

 certain insects occur in buildings, fumigation with hydrocyanic acid gas is the most 

 effective mode of eradication. In many of our Canadian flour mills very serious losses 

 are incurred by the presence of the Mediterannean Flour Moth, Ep'hestia huehniella 

 Zell, which may also occur in warehouses. We have also received specimens of the 

 larvae of the Spider Beetle {Ptinus fur L.) from flour mills in llanitoba and Saskat- 

 chewan. These and other mill infesting insects, but not all species, can be destroyed 

 successfully by fumigation. Occasionally houses may become seriously infested "with 

 a species of insect which it may be desirable to eradicate: such eradication can be 

 effected only by fumigation. 



Fumigation is effected by hydrocyanic acid gas which is generated in the building. 

 This gas is one of the most deadly poisons existing and consequently the greatest care 

 must he taken in carrying out these fumigation operations, otherwise the results may 

 he fatal. 



Before fumigating a building, all the openings to the exterior, except the door, 

 must be sealed up. Cracks and crevices may be filled with wet paper or covered with 

 strips of paper and the room or rooms made gas-tight. Provision must be made for the 

 ventilation of the room or rooms from the outside after fumigation. All moist foods 

 and liquids should be removed before fumigation or they may take up the poison. 

 Where mills are to be fumigated they should be thoroughly cleaned previous to fumi- 

 gation. The cubical contents of the space to be fumigated must be calculated by 

 multiplying the height of the chamber or room by the length and this by the breadth; 

 this will give the number of cubic feet. 



The gas is generated by adding dilute sulphuric acid to potassium cyanide. In 

 practice this is reversed. The proportion of the chemicals are as follows for every 

 100 cubic feet of space: — 



Potassium cyanide 1 oz. by weight. 



Commercial sulphuric aci.l 1 " " 



Water 2 fluid ozs. by measure. 



The potassium cyanide must be 98 per cent pure. The sulphuric acid should 1 o 

 concentrated, having a specific gravity of 66 degrees Beaume. If the building is poorly 



