No. 6. DEPARTMENT OF AGRICULTURE!. 73« 



tering of the beetles. When the plants appear again, if the plague *i 

 beetles continues to threaten their destruction, a ridge of soil may be 

 thrown over the rows. It will do no injury, and when the plants 

 emerge again a weeder should be used to level the laud. By this 

 time the thriftiness of the plants will usually put them beyond 

 serious danger so far as the brood of old beetles is concerned. 



The grower then has opportunity of mastery, and if he succeeds as 

 thoroughly in d'estroying the larvae of the first brood as he should 

 do, there will be no second brood to do injury late in the summer. 

 The one practical method of killing the larvae or grubs — the 

 "young bugs" — is by poisoning. The Maine Station made experi- 

 ments with various insecticides and reached the conclusions that 

 ■'in fighting the Colorado potato beetle no adequate substitute for 

 arsenical poisons has yet been found.'' The efl'orts are now limited 

 to finding cheaper or more effective compound's of arsenic than Paris 

 green. There are many preparations ui)on the market, some of 

 which are good and some are poor. A good preparation has strength, 

 remains in suspension in water well, and is not soluble, as is white 

 arsenic, which may burn the foliage. Where a high-grade article of 

 Paris green can be bought at a fair price, it may be safely recom- 

 mended. Where there is no state inspection of this poison, the 

 buyer should test his purchase before making application to the field. 

 A few early-hatched grubs are sure to appear, and within a few hours 

 the relative strength of the poison may be learned. 



Arsenites in Water. — The most common way of applying arsenites 

 is in water, four to six ounces of Paris green being used in fifty gal- 

 lons of water. The fonner amount is sufficient for very young grubs, 

 but the latter should be used if by any chance the grubs are half- 

 grown when the application is made. It is a mistake to delay apply- 

 ing the poison until any grubs are half-grown. This is often done in 

 the plea that all should be hatched out so that one application will 

 serve. But when any of the grubs have reached such a stage of 

 growth, some will not be killed by the poison. They are scattered 

 over the vines, and find some leaves sufficiently free from poison to 

 escape death, and these become the beetles that give us the second 

 brood of grubs which often do much harm. More than this, the eat- 

 ing of the leaves checks the vigor of the plants. The arsenite should 

 be applied when the grubs appear, and if it does not adhere to the 

 vines until all are hatched, a second application should be made. 

 The arsenite should be thoroughly mixed with water in a large bottle, 

 and then emptied into the barrel. 



Sprayers. — Devices for applying insecticides in liquid form are 

 luany. It is my experience that the knapsack sprayer is better 

 adapted to gardens and small fields than to an extensive acreage, but 

 it does good, thorough work. The spraying apparatus that covers 



