Xew York Agricultural Experiment Station. 267 



paid. A few of the remedies are distasteful to the beetles, but the 

 difficulty of applying them to all parts of the plants, makes their 

 use only a partial success. When the beetles are frightened from 

 the plants they usually return in a short time. They may not 

 appear to be as numerous, but they will be found scattered over 

 the entire field and hidden in the loose dirt, gnawing off the stems 

 below the surface of the ground. Even the best of these rem- 

 edies, applied when the beetles first make their appearance, will 

 be found nearly worthless if tested alone ; in fact, there are times, 

 except where a trap-crop is used, when nothing but a good wire 

 cover will prevent their damaging the vines. I have even seen 

 them gnaw holes in cloth covers to get at the plants. x\t such 

 times they should have all the poisoned squash plants they will 

 eat. 



(1) Bordeaux mixiure}'^ — One of the best remedies for mak- 

 ing the vines distasteful to the cucumber beetle is Bordeaux mix- 



17 During the past few years entomologists and mycologists have been recom- 

 mending the use of Paris green with Bordeaux mixture for various insect, 

 for the following reasons: There is less danger of injury to the foliage from 

 the Paris green; the Bordeaux mixtuie helps to retain the poison on the foliage 

 longer than Paris green alone would adhere; and, lastly, the application of a 

 fungicide and an insecticide at one and the same time is a saving worth look- 

 ing after. 



Observations and tests on potato and cucumber beetles convince me that if 

 we desire to kill these pests, the Paris green must be used alone, before the 

 Bordeaux mixture is applied. 



In I80G, several tests were made on the Colorado potato beetles, to determine 

 efTects of Bordeaux mixture as an insecticide. To be sure in each case that 

 every part of the potato plant was thoroughly covered, they were dijjped in 

 the Bordeaux mixture, after which they were placed in a breeding cage and a 

 large number of young potato beetles placed on them. Although the plants 

 were kept fresh, not one of the beetles would feed upon them, and all finally 

 starved to death. This test was repeated three times with the same result in 

 each case. The question arises, why not use the Bordeaux mixture as an in- 

 secticide? The difficulty is that in the field it is impossible to get the mixture 

 onto all parts of the plants, the result being that potato and cucumber beetles 

 can find places to feed without touching the Bordeaux mixture. Hence, it is 

 seen that when Paris green is used with Bordeaux mixture to kill the above 

 leaf-eating beetles, the value of the Paris green is destroyed. If we wish to 

 kill these pests, 'the Paris green must be applied alone. 



