COCKROACHES AND HOUSE ANTS. 93 



of the domestic species, and its injuries to food products, books, etc., 

 and the disgusting results of its presence in pantries, storehouses, and 

 bakeries, give it really a greater economic importance than any of the 

 other species. 



It is very light brown in color, and characteristically marked on the 

 thorax with two dark-brown stripes. It is more active and wary than 

 the larger species and much more difficult to eradicate. It is tlie 

 smallest of the domestic species, rarely exceeding five-eighths of an 

 inch in length, and multiplies much more rapidly than the others, the 

 breeding period being shorter and the number of eggs in the capsules 

 greater than with the larger roaches. The injuries effected by it to 

 cloth-bound reports have been the source of very considerable annoy- 

 ance at the Department of Agriculture and in the large libraries of 

 Eastern towns and colleges. The characteristics of the different stages, 

 from the egg to the adult, are shown in the illustration (fig. 42). 



REMEDIES. 



Like the crows among birds, the roaches among insects are appar- 

 ently unusually well endowed with the ability to guard themselves 

 against enemies, displaying great intelligence in keeping out of the 

 way of the irate housekeeper and in avoiding food or other substances 

 which have been doctored with poisons for their benefit. Their keen- 

 ness in this direction is unquestionably the inheritance of many cen- 

 turies during which the hand of man has ever been raised against 

 them. 



The means against these insects, including always vigilance and 

 cleanliness as important preventives, are three, namely, destruction by 

 poisons, by fumigation with poisonous gases, and by trapping. 



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

 of the presence of poisons in food, and, notwithstanding their practi- 

 cally omnivorous habits, a very little arsenic in baits seems to be 

 readily detected by them. In attempting to eradicate roaches from 

 the Department storerooms where cloth-bound books are kept various 

 paste mixtures containing arsenic Mere tried, but the roaches inva- 

 riably refused to feed on them in the least. This applies particularly 

 to the German roach, or Croton bug, and may not hold so strongly 

 with the less wary and perhaps less intelligent larger roaches. 



A common remedy suggested for roaches consists in the liberal use of 

 pyrethrum powder or buhach, and when this is persisted in consider- 

 able relief will be gained. It is not a perfect remedy, however, and is 

 at best but a temporary expedient, while it has the additional disad- 

 vantage of soiling the shelves or other objects over which it is dusted. 

 Wlien used it should be fresh and liberally applied. Roaches are often 

 paralyzed 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 paralyzed roaches swept up and burned. 



