ENTOMOLOGY 275 



quantity of water into a fine paste before the bulk of water is added 

 and should be churned in the sprayer or force pump until thoroughly 

 blended. The resulting mixture, being a mechanical one, is not 

 constant and the arsenical sinks to the bottom. The solution should 

 therefore be constantly stirred while being; applied in order that an 

 even application may be made. In applying an arsenical spray an 

 effort should be made to reach all of the leaves, which may be accom- 

 plished by spraying from two sides. Two or three applications will 

 suffice for the spring generation of rose slugs. Scheele's green and 

 some other arsenicals can be used instead of Paris green. 



A still more valuable insecticide for such insects as rose slugs and? 

 other leaf feeders is arsenate of lead, but its use is open to the objec- 

 tion that it discolors the leafage, leaving a white deposit, which is not, 

 however, permanent. It is applied in practically the same manner 

 as Paris green and is a less poisonous arsenical, and, being sold in 

 paste form, is used at a considerably greater strength about 1 pound 

 combined with 15 to 25 gallons of water or Bordeaux mixture. JBeing 

 adhesive, it adheres more firmly to the leafage and is much less likely 

 to produce scorching. 



Hellebore is used at the rate of 1 ounce to from 2 to 3 gallons of 

 water, and kills by contact as well as by its poisonous effects when 

 eaten by the insect. It is less poisonous to man than an arsenical, 

 but not so effective to leaf-feeding larvae. It may also be applied dry 

 mixed with about double its weight, or more, of powdered plaster or 

 cheap flour. 



When not in use the receptacles containing poisons should be 

 plainly labeled Poison ! and placed on a high shelf or in a locker out 

 of the reach of children. Properly applied, there is no danger, in 

 using an arsenical on ornamental plants, of poisoning human beings, 

 or domestic animals other than rabbits or similar pets. 



Oily soaps, such as fish-oil or whale-oil soap, and other soaps, 

 and tobacco water will kill these insects, but their use is open to the 

 objection that if applied just before or at blossoming they are apt to 

 injure the petals of delicate flowers, and whale-oil and tobacco also 

 leave an unpleasant odor. A neutral soap, such as castile or that used 

 by physicians and surgeons, leaves no odor. 



If rose slugs are picked off by hand upon their earliest appear- 

 ance this will greatly reduce their numbers for the following year. 

 In the adult or fly stage these insects may be easily captured by hand 

 on cool mornings. Hand picking may be tedious, but it is effective. 



If other means that have been specified have not been utilized 

 for the suppression of the slugs, many individuals may be destroyed 

 by frequent cultivation of the soil between the rose plants during tho 

 late summer and autumn. This has the effect of breaking up their 

 pupal cells and otherwise disturbing the insects so as to interfere with 

 proper hibernation. 



The Bristly Rose Slug. The bristly rose slug, called also the 

 spiny rose slug, is the principal enemy of the rose in and near the 

 District of Columbia, not excepting trie rose-chafer. The adult of 

 this species differs considerably from that of the American rose slug. 



