New York Agricultural Experiment Station. 335 



Test No. 4, with Hyphantria cunea. was designed to determine 

 the insecticidal values of mixtures after three days' exposure to 

 weather. The sprays applied were lead arsenate, paste, with water, 

 bordeaux, lime-sulphur, soap and glucose; and zinc arsenite with 

 water, bordeaux, lime-sulphur, soap, glucose and lime. Trees in the 

 orchard were spraj^ed on Aug. 14 and on Aug. 17 foliage was removed 

 from the trees and fed to insects. The rate of action of the mixtures 

 and the extent of feeding are shown in Table II. 



Results. — There was very little difference in the rate of action of 

 the poisons except when arsenate of lead was used in combination 

 with lime-sulphur or glucose. These proved less effective, although 

 the amount of foliage actually consumed was greater than with the 

 other lots. This suggests that during the interval of three days' 

 exposure the mixture of lead and lime-sulphur had lost some of its 

 effective properties. The minimum feeding occurred when arsenate 

 of lead was used alone or with bordeaux, and when zinc arsenite 

 was used with lime or bordeaux mixture. 



Test No. 5, with Hyphantria cunea. — This test is identical with 

 No. 3 except that the sprayed trees were subjected to the weather 

 for eight days. The trees were sprayed July 30 and the foliage fed 

 to the insects on Aug. 7. As will be seen from the weather record, 

 page 6, there occurred in this interval four showers aggre- 

 gating, 24 inch. 



Results. — All the sprays were still effective as insecticides, though 

 the glucose with lead arsenate had lost some of its poisonous prop- 

 erties. In the eight days' exposure there was a partial loss of 

 the repellent action of some sprays and generally much more feeding 

 than in test No. 3. The minimum feeding occurred with lead 

 arsenate and glue and with the combinations in which soap and 

 bordeaux were used. The area of leaf surface consumed was at 

 least three times greater with mixtures containing lime-sulphur than 

 with mixtures containing bordeaux, which is a marked contrast to 

 what occurred in Test 3. This indicates, as did other tests, that 

 lime-sulphur loses its repellent properties sooner than the sprays 

 that contain soap and bordeaux mixture. The maximum feeding 

 occurred where either lead arsenate or zinc arsenite was used alone 

 or in combination with glucose. 



Test No. 6, with Hyphantria cunea. — This is similar to Nos. 3 

 and 5 except that the sprayed foliage used in this feeding test had 

 been exposed to the weather for twenty-five days. The trees were 

 sprayed July 30 and the foliage brought to the laboratory Aug. 24. 

 The sprayed foliage used in this experiment had been subjected 

 to the washing action of 1.88 inches of rain from twelve showers 

 occurring during the interval. 



Results. — The combinations that were still distinctly effective were 

 those in which glue and bordeaux were used and the zinc arsenite 

 and soap mixture. On the contrary, zinc arsenite, lead arsenate, 



