THE CANADIAN ENTOMOLOGIST. 171 



The Colorado potato beetle may also be attacked with greatest success 

 in the larval state. The integuments are then soft, and the appetite more 

 voracious, so that whether the poison by contact or the poison by food be 

 used, it will have a more certain effect than upon the perfect insect, which 

 is protected against the former by the hard chitinous surface and against 

 the latter by preoccupation in reproductive duties. 



You will be prepared to admit the importance of the recommendation 

 above made, that the times for making the attack should be directed by 

 the scientific commission after full examination of the habits of the insects 

 and the dates of their appearance in their various stages of developement. 

 These dates will vary in different districts, and without a carefully 

 tabulated calendar of the necessary facts, no system of combined effort, 

 such as I believe to be essential, can be planned. 



The apparatus to be used must of course vary greatly with the habits 

 of the insects to be attacked. In the case of the plum curculio canvas 

 frames propelled on a kind of wheelbarrow, with a ram to concuss the 

 trunk of the tree, is probably the best instrument yet devised. The 

 insect will fall into the net when the tree is struck, and may be easily 

 destroyed when a sufficient mass has been collected. For the cotton 

 moth and the potato beetle the apparatus for poisoning the leaves upon 

 which they feed may be any simple sprinkler or dusting box, according as 

 liquid or solid poison is employed. But for direct application to the 

 insect itself, we must use means by which a fine spray will be driven with 

 force sufficient to envelop the whole plant, or the surface of the ground 

 upon which the insects are assembled, in a mist of poisonous liquid. 

 Such an instrument is the atomizer, which has the additional advantage 

 over the sprinkler that it consumes less liquid. The first application of 

 the atomizer for the destruction of insects was made by me several years 

 ago, and in the American Naturalist for August, 1869, 1 published a short 

 paper recommending its use with certain poisonous liquids for the disin- 

 fection and preservation of insect cabinets. I have seen its frequent use 

 with great success. 



When the question of locusts became of importance last year, and the 

 Colorado potato beetle began to be very troublesome in the Atlantic 

 States, I spoke with several commercial friends and others about the 

 propriety of making atomizers of large size for the destruction of these 

 pests. In consequence of delay in the measures they thought necessary 

 to command the attention and security of a manufacturer, no progress 



