18 ALFRED E. CAMERON. 



The total destruction of the flea-beetle, like that of any other insect pest, would 

 mean unlimited expenditure and is practically impossible. As an insect indigenous 

 to the United States, this pest will for ever, as long as potatoes are grown, levy a 

 tax upon the farmer ; so that the question resolves itself into one of reducing the 

 tax to a minimum by some measure of control. Three principal methods of attack 

 have been employed in abating injurious insect pests, classified as follows : — 



(1) Treatments which kill the insects ; 



(2) measures that will restrict their abundance and act temporarily as 



repellants ; 



(3) natural checks, such as insect or fungous parasites. 



Hitherto it has been the general plan to tackle the problem of flea-beetle control 

 by means of repellants, and although arsenate of lead and Bordeaux mixture have 

 on many occasions proved efficient, several of the inert powders and dusts recommended 

 are practically of little benefit. Because of its activities and peculiar habits, the 

 problem of killing the insect outright presents many difficulties. It is essential 

 for the rapid administration of a lethal dose, that the material employed must actually 

 hit the insect and be retained there until the animal is paralysed beyond recovery. 

 What I have in mind is pyrethrum mixed with an adhering agent such as gelatin, 

 glue, or soap. After some experiments had been carried out in the laboratory with 

 several different substances hereafter tabulated, it was decided to try some of 

 these on early and late potatoes with a view to discovering an agent capable 

 of killing the beetles quickly. An infusion of pyrethrum mixed with lead 

 arsenate in which gelatin is incorporated, gave most satisfactory results. This 

 combination insecticide is made up in the proportion of 6 lb. of pyrethrum to 

 60 gals, of water, to which sufficient gelatin or soap is added to ensure that a film of 

 the liquid will adhere readily, when sprayed on the leaves. In preparation, the 

 pyrethrum is first made into a paste by the addition of hot boiling water, then diluted 

 with hot water and cooled, and then further diluted to the required strength with 

 cold water, the gelatin solution being previously stirred in. To get the best results, 

 this insecticide should be applied at 100 lb. pressure so that it hits the plants as a 

 fine mist. 



There is one circumstance which appears to be worthy of attention. In spraying 

 or dusting against the flea-beetle, it is the custom to have the operating machine 

 drawn by the horses between the rows of the potato plants. On account of the 

 great activity of the pest and its readiness to escape at the slightest disturbance, it 

 was observed that the movement of the team caused the beetles to clear away 

 from the foliage before the spray fluid could reach them. Therefore, if it could 

 be contrived, it would be a decided advantage to have the machine pushed between 

 the rows, instead of drawn. 



The laboratory experiments were carried through in lamp-globes covered with 

 muslin. Inside the globes a small vessel for holding water was placed, into which slips 

 cut from the potatoes and treated with the various preparations tabulated, were put. 

 Flea-beetles in varying numbers, which were always previously counted, were then 

 introduced and the effects noted after a period of hours or days, as the case might be. 

 The penultimate column of the table which follows records the percentage mortality, 



