54 



This description, or rather these distinctions, of Mr. Chambers apply 

 to some examples, while to others they do not. Many specimens are 

 very roseate and richly colored, while a few appear almost plain black 

 and dull white. The three species are best distinguished in the larva 

 state, in which there are very decided differences. G. roseosuffuseUa 

 feeds on Clover, G. rubensella on Oak, while the species under con- 

 sideration, so far as my observations show, is confined to Apple. The 

 larval characters are also very diverse in the three species. 



EXPERIMENTS WITH INSECTICIDES. 



During the great prevalence of ApMdidce in the spring I made much 

 use of pyrethrum and of the X. O. dust. Of the value of the former as 

 a remedy for these pests, except in the case of one or. two species, I 

 have no occasion to change the favorable opinions already repeatedly 

 published. The X. O. dust was thoroughly tested on the following 

 Aphids: Aphis maliand Schizoneura lanigera on Apple; Aphis prunifolii 

 on Plum; Siphonophora rosce on Bose; Myzus persicce on Peach; Ap>his 

 brassicce on Cabbage; Aphis sp.? on Cucumbers and Squash; Siphono- 

 phora sp. J ? on Lettuce; S. cratcegi on Thorns; S. rudbechice on Solidago; 

 Aphis ambrosice on Ambrosia triflda, and Aphis chrysanthemif on Chrys- 

 anthemum. With its effects on all of these I was well satisfied, although 

 in some cases it took several dustings to thoroughly clear a plant. 

 When applied with a powder bellows it causes the insects to drop to the 

 ground at once, where they may be pressed into the soil with the foot or 

 patted down with a trowel. The more delicate species succumb to a 

 single thorough dusting and never recover from the effects of contact 

 with the powder. This preparation will also destroy Siphonophora 

 avenw, but whether it could in any way be applied to a field of infested 

 grain has not been demonstrated. 



The Black Chrysanthemum Aphis is one of the greatest pests of the 

 flower garden and gives much trouble to both amateurs and profes- 

 sional florists. It hibernates on the plant and attacks the stolons as 

 soon as they appear in the spring, and unless great care is taken to 

 eradicate it, it is more or less numerous on the plants throughout the 

 summer, dwarfing and deforming them by its punctures and by the loss 

 of sap which it appropriates. As soon as the buds are formed it seems 

 to develop with four-fold fecundity and requires assiduous attention to 

 keep in check. The Buhach or pyrethrum powder is utterly useless 

 against this species, probably because the plant from which it is made 

 is so close an ally of the Chrysanthemum. The X. O. dust, composed 

 of creosote and tobacco, is the best remedy within my knowledge, killing 

 the Aphis without the slightest injury to the plant. I have found it 

 best to apply during the middle of the day when the dew is off. A few 

 minutes after dusting the plants, I pass along the rows or among the 

 pots, and give each branch a smart shake or a blast of air from the 

 empty puff, and every Aphis that has not previously dropped is dis- 



