THE HAWAIIAN BEET WEBWORM. 9 



September 12, all the larvae which had not matured were still feed- 

 ing and showed no ill effects from their diet of arsenate of lead and 

 Amaranthus leaves. The spray mixture caused no injury to the 

 foliage. 



In this test a standard grade of arsenate of lead was used at the 

 rate of 6J pounds in 100 gallons of water, and it is difficult to under- 

 stand why it failed to kill the tender Hymenia larvae. Of course, 

 such a test as this can not be considered conclusive, but it would indi- 

 cate that less effective results would be obtained with arsenate of lead 

 than with Paris green. 



Experiment No. £. — Lime-sulphur solution, 1 gallon, in 15 gallons 

 of water. November 1, a few infested beets were sprayed with a small 

 quantity of this solution. A thorough application was made to the 

 upper surface and underside of the leaves with an atomizer. Larvae 

 which were drenched with the solution appeared to die promptly. 

 The weather was hot and clear at the time of the application. Two 

 days later the larvae had been reduced somewhat in numbers but there 

 were still plenty of living specimens present. Some of the leaves 

 were severely burned. November 5, the coat of lime was still very 

 good. The larvae were feeding on the coated leaves and were appar- 

 ently unharmed. This solution apparently killed only the larvae 

 which were thoroughly drenched at the time of the application. The 

 beet foliage was severely burned, and on the whole the results were 

 not promising. 



Experiment No. 5. — Lead chromate, 2 ounces, in 8 gallons of water. 

 December 16, a few infested beets were sprayed with a small quan- 

 tity of this mixture. The application was made to the upper and 

 lower surfaces of the leaves with an atomizer. The mixture ap- 

 peared as a yellow coating on the leaves and adhered very well. The 

 weather was hot and clear. Three days later the larvae were still 

 alive, but had ceased feeding, and were clinging to the leaves in a 

 listless manner. During the following two or three days they 

 dropped to the ground and died. The sprayed foliage showed no 

 burning. It is not possible to form a definite conclusion from this 

 meager test, but it indicates that lead chromate at this strength is 

 very slow in its killing effects. 



In another similar test lead chromate was used on beets at the 

 rate of 2 ounces in 4 gallons of water. L T nfortunately an illness of 

 the author prevented the making of observations as to the effect of 

 this strength on the larvae. Ten days after the application it was 

 noted that two heavy rains had failed to wash the coat of poison 

 from the leaves and that no burning had resulted. It is evident 

 that this new insecticide has some good points, and it should be 

 given a thorough trial. 



