133 



The earlier experiments were inconclusive owing to the Nicodust 

 used, not being of uniform strength. During the observations made 

 in 1921, three days after the application of a mixture of freshly 

 burnt lime and 10 per cent. Black-leaf 40 there was a reduction of 

 84 per cent, of the leaf-hoppers. An average of 92-6 per cent, of leaf- 

 hoppers in cages were dead 48 hours after treatment with freshly made 

 dust containing 10 per cent. Black-leaf 40. Dust about 6 weeks old, 

 even when kept in closed tin receptacles, is less effective than when 

 freshly made. As beets were planted after the invasion into the 

 cultivated area had already occurred, no satisfactory conclusions can 

 be drawn as to the value of dust mixtures. The first appUcation was 

 made on the 20th June, and the second on the 24th June, after the 

 second brood nymphs had hatched. 



It is evident, however, that with a reduction of 84 per cent, of the 

 leaf-hoppers in a dusted acre of beets, a marked decrease in the per- 

 centage of curly leaf would occur in isolated beet-fields, provided that 

 the dust is applied shortly after the spring flight of the adults into the 

 cultivated area. 



Smith (R. H.). Annraphis helichrysi Kalt, a Pest of Prune, Plum, 

 and Red Clover in Idaho. — //. Econ. Ent. Geneva, N. Y., xiv, 

 no. 5, October 1921, pp. 422-423. [Received 13th January 1922.] 



Annraphis helichrysi, Kalt., is the most important Aphid affecting 

 prunes and plums in Idaho. The chief summer food-plants are red 

 clover, Trifolium pratense, garden varieties of Aster, Chrysanthemum, 

 Dahlia, and Erigeron canadensis. All varieties of prune and plum 

 are susceptible to attack. Occasional colonies found in the spring 

 on peach and apricot did not thrive as well as those on prunes and 

 plums. Small numbers of this Aphid have also been observed on 

 Achillea millefolimn, Solidago serotina, Trifolium hybridum and 

 T. repens. 



The migrant females and males begin developing on the summer 

 food-plants during the latter part of August at an altitude of 3,700 feet. 

 By the 15th September they occur in abundance on foliage of prune and 

 plum. Oviposition occurs at the bases of the buds and on the bark 

 of the branches. The eggs hatch early while the buds of prune and 

 most varieties of plum are entirely dormant and those of peach only 

 slightly swollen. The stem-mothers feed at the bases of buds and on 

 the bark of the last season's growth imtil the fruit buds begin to open. 

 They begin reproducing about the time green tips appear on the fruit 

 buds of prune. Migrants occur chiefly in the third and succeeding 

 generations. On prune and plum the Aphids are strictly leaf feeding, 

 but on red clover and other summer food-plants, the concealed parts 

 of stems, petioles and blossoms are mostly attacked. The infested 

 leaves of prune and plum curl tightly and develop numerous pocket- 

 like galls. New leaves at the tips of infested branches curl as soon 

 as they develop. The new growth of these branches is stunted and 

 malformed and there is apparently a tendency for the fruit to drop 

 prematurely. The Aphids do not spread readily from one part of a 

 tree to another. 



A . helichrysi may be controlled by spraying with |-pint Black-leaf 40 

 to 100 U.S. gals, water, with soap as a spreader, or to 100 U.S. gals, 

 of dilute lime-sulphur solution. The spray should be applied just before 

 the buds of prune and plum open. The eggs and stem-mothers cannot 

 be effectively controlled by lime-sulphur at winter strength. 



