THE ORTHOPTERA OF MINNESOTA. ;53 



Poisons. — "As just noted, roaches often seem to display 

 a knowledge of the presence of poisons in food, and, not- 

 witiistanding their practically omnivorous habits, a very 

 little arsenic in baits seems to be readily detected by them. 

 In attempting to eradicate roaches from the department 

 store-rooms where cloth-bound books are kept, various paste 

 mixtures containing arsenic were tried, but the roaches in- 

 variably refused to feed on them in the least. This applies 

 particularly to the German roach, or Croton bug, and may 

 not hold so strongh' with the less wary and perhaps less 

 intelligent larger roaches. 



A common remedy suggested for roaches consists in the 

 liberal use of pyrethruni powder or buhach, and when this 

 is persisted in considerable relief will be gained. It is not a 

 perfect remedy, however, and is at best but a temporary 

 expedient, while it has the additional disadvantage of soil- 

 ing the shelves or other objects over which it is dusted. 

 When used it should be fresh and liberally applied. Roaches 

 are often paralized by it when not killed outright, and the 

 morning after an application the infested premises should 

 be gone over and all the dead or partially paralized roaches 

 swept up and burned. 



There are many proprietary substances which claim to 

 be fairly effective roach poisons. The usefulness of most of 

 these is, however, ver\' problematical, and disappointment 

 \vill ordinarily follow their application. The onh^ one of 

 these that has given very satisfactory results is a phos- 

 phorous paste, also sold in the form of pills. It probably 

 consists of sweetened flour paste containing phosporous, 

 and is spread on bits of white paper or cardboard and 

 placed in the runwa3^s of the roaches. It has been used 

 very successfully in the department to free desks from Croton 

 bugs, numbers of the dead insects being found in the drawers 

 every day during the time the poison was kept about. 



Fumigation. — Whenever roaches infest small rooms 

 or apartments which may be sealed up nearly air- 



