438 



AJV ECONOMIC ENTOMOLOGY. 



such cases the addition of one pound of soap to every forty or 

 fifty gallons of water will aid matters considerably. The mixture 

 will spread much more completely, and will adhere even to very 

 smooth or feathery foliage if a fine spray nozzle is employed. 

 One quart of molasses or, better, glucose in every fifty gallons 

 of water will also greatly increase the adhesive and lasting quali- 

 ties of any mixture employed. 



These arsenical poisons act only through the stomach, and no 

 insects are able to resist them entirely, although some bear a 

 considerable amount without showing immediate effects. When- 

 ever they are available, it will pay to use them to the exclusion 

 of other materials. There is no other stomach poison that com- 

 pares with them. And here it may be advisable to say a few words 

 concerning a great many ' ' harmless' ' insecticides placed upon 

 the market. 



As a matter of fact almost all the commercial insecticides other 

 than pastes or soaps contain arsenic in some form or shape, and 

 this is in most instances the killing agent. It is also quite true 

 that under ordinary circumstances the preparations are ' ' harm- 

 less" to man, because in so diluted a form. As these poisons 

 are used upon plants, the proportion is so small that danger to 

 life is not to be anticipated, except as a result of the grossest 

 carelessness ; hence, strictly speaking, the mixtures are ' ' harm- 

 less," though containing arsenic. The purchaser, however, usu- 

 ally pays at least three prices, and, in addition, freight charges 

 upon a mass of inert diluting matter. 



There is another way of using the arsenites which should be 

 briefly referred to here, — i.e., in a poisoned bran mixture, to 

 attract cut-worms and some other insects to a deadly feast. Mix 

 one pound of Paris green, or half as much white arsenic, with 

 fifty pounds of bran, making the combination as perfect as pos- 

 sible ; then add water enough to moisten thoroughly, so that the 

 mixture can be ladled out with a spoon without dripping. A 

 little sugar or molasses in the water makes the mass rather more 

 adhesive and lasting, but apparently no more attractive to the 

 insects. How this mixture should be used will be found stated 

 in those cases where its employment is indicated. 



Bichloride of mercury, or ''corrosive sublimate," is an ex- 

 tremely violent poison, of which some use has been made, but 



