64 Till-: JJH(AVN-TA1L .MOTH. 



Insecticides. 

 For the work of spraying tlie foliage, no poison is more 

 effective than tlie arsenate of lead. This material is of light 

 specific gravity, hence remains well suspended in the spray- 

 injr solution, and insures an even distribution on th(^ foliai::e. 

 It does not kill (juitc as (quickly as Paris green, but is very 

 etfective against the insects Avhen used in the proportions 

 directed. It has two special advantages, in that it sticks to 

 the foliage tenaciously throughout the season, and will not 

 scorch or injure the most delicate leaves. It is slightly 

 more expensive than Paris green or London purple, if the 

 first cost of the material only is consid(!red. On the other 

 hand, as one spraying is often sufficient to preserve a tree 

 unharmed from leaf-eating insects for an entire season, while 

 repeated sprayings of Paris green are necessaiy, the arsenate 

 of lead often proves the cheaper insecticide. 



lloir iji((di\ 



Arsenate of lead may be prepared by dissolving separately 

 H i)arts commercial nitrate of lead and 1 part commercial 

 arsenate of soda and pouring the two solutions together, 

 when the arsenate of lead is fluni; down as a dense white 

 precipitate. This fornmla is based upon the average grade 

 of nitrate of lead containing (36.5 per cent, lead oxide, and 

 arsenate of soda containing 59.8 per cent, arsenic oxide. 

 Owing to the ditliculty in obtaining these chemicals in small 

 (juantities at a fair })rice, and the uncertainty as to their 

 purity, the small user will do well to purchase some one of 

 the prepared forms of arsenate of lead now otl'ered in the 

 market, instead of attemi)ting to manufacture the insecticide. 

 Owing to the increasing use of arsenate of lead for si)raying 

 purposes, several reliahle manufacturers have j)ut it uj)on 

 the market in the form ol" a }):iste, \\hi<'h is ready foi- use as 

 soon as water is added, thus being at once convenient and 

 inexpensive. 



If Paris green is used, a strength of 1 pound to 150 gal- 

 lons of water will give good results, and the projjortion of 

 poison should not be greater than 1 jjound to !(»() gallons, 



