246 



THE AMERICAN ENTOMOLOGIST. 



effects a few hours after application and 

 particularly the day following. In the 

 early use of the Green the same diversified 

 experience was had, and from defective 

 methods or adulterated material unfavora- 

 ble results were quite frequent. One 

 source of failure with both these materials 

 in liquid is the lack of provision to keep 

 them stirred up and well suspended ; 

 another, in not bearing in mind that the 

 poison has greater specific gravity than 

 the water in which it is carried, so that in 

 poisoning many rows at a time the finer 

 spray falls on the furthermost rows with 

 little or no poison. 



London Purple is exceedingly fine and 

 sifts through the slightest crevice. This 

 is an advantage to the planter who uses it 

 on his cotton, but necessitates great care 

 in shipping. The manufacturers have 

 shipped it for the most part in barrels 

 which have permitted it to leak and stain 

 other goods as well as the vehicles of 

 transport, thus doing more or less injury 

 and prejudicing freight agents against it. 

 This defect should be remedied. 



Experience seems to indicate that it is 

 less dangerous to use than Paris Green. 

 I know of two negroes who stole some 

 flour in which it had been mixed in the 

 ordinary proportion for use on cotton, and 

 made biscuits thereof. Both were made 

 sick but neither seriously, and Prof. Bar- 

 nard found that the steward on one of the 

 Mississippi steamboats (the decks of which 

 get quite purple from carrying it) has 

 made regular use of the wastage so easily 

 obtained on every hand for coloring his 

 pastry and ice cream. That no ill results 

 have followed is no reason for perpetuating 

 the practice. Some of the unfavorable 

 experience with this Purple I am con- 

 strained to believe has resulted from ad- 

 ulteration. 



PVRETHRUM. 



This powder of which, since last year's. 

 experiments I have Tiad great hopes, fully 

 warrants them. No other vegetal sub- 

 stance approaches it. Last year, while it 

 was found by Prof. Hilgard of California, 

 that an alcoholic extract of any part of 



the plant possessed the insecticide proper- 

 ty, I had serious doubts whether it could 

 ever be successfully used in the cotton 

 field because of its cost. The simple pow- 

 der mixed with flour as a diluent could 

 then be made to go over more ground than 

 the alcoholic extract. The present year 

 we have found that an ordinary fluid ex- 

 tract made after the ordinary formula of 

 the pharmacopasa will go much farther 

 and that the extract from a pound kills 

 all young worms when diluted in 120 

 gallons of water ! Nay, more, one of 

 the most important discoveries is that it 

 acts equally well, or even better, simply 

 mixed in water; and even one pound to 

 150 gallons is effective, and one pound to 

 200 gallons will cause the destruction of 

 most young worms. Its action is really 

 marvelous ; but, as it kills by contact, its 

 effects are not lasting as in the case of 

 arsenical poisons which act through the 

 stomach. It produces convulsions, and 

 paralyzes, so that all young worms it comes 

 in contact with soon writhe to the ground. 

 Larger worms are less easily affected, but 

 they too writhe to the ground, from which 

 they rarely recover, even if the Pyrethrum 

 fails in the end to kill; for, once on the 

 ground and enfeebled, a host of enemies 

 are ever ready to finish the work begun by 

 the powder. This insecticide acts quite 

 differently on different insects, but Aletia 

 is one of the most susceptible to it. 



I have not a doubt but that when it is 

 once produced in this country so that the 

 cost of the powder will be nominal, it will 

 be extensively employed by planters, and 

 to this end I have taken steps to have it 

 introduced and cultivated. Its harmless- 

 ness to man, the small quantity necessary, 

 and the fact that it may be grown by the 

 planter himself, will offset the greater per- 

 manency of the arsenical powders. 



OILS. 



Nothing is more deadly to the insect in 

 all stages than kerosene, or oils of any 

 kind, and they are the only substances with 

 which we may hope to destroy the eggs. 

 In this connection the difficulty of diluting 



