National Geographic : 1917 Jul
Photograph from U. S. Public Health Service THE POISON SQUAD SETTING OUT These men, who are chosen especially for their reliability and carefulness, are setting out to distribute the poison "croutons." A record is kept of each place where poison is placed. investigation, the estimated average an nual loss caused by each rat was com puted to equal $1.80 in Great Britain, $1.20 in Denmark, and $I in France. In the United States the average is undoubt edly much larger than in any of the coun tries named, especially at present high prices of food and other merchandise. There is no doubt that a very large number of rats subsist wholly on garbage and waste which is of no value, but the damage caused by rats in numerous places amounts to many dollars each a year; probably $5 a year would not be an over estimate for the average loss caused by each rat living in a dwelling, hotel, res taurant, or other place having ready ac cess to food supplies. Assuming, roughly speaking, that as estimated the rat population in the United States is 50,ooo,ooo for the cities and 150,000,000 for the rural districts, it will require the destruction of property by each rat of only a little more than one fourth a cent a day to make the aggregate great sum estimated as destroyed by these pests yearly in this country. In 1907 a careful survey was made of the damage done by rats in Washington. More than 500 business establishments, including factories, stores, livery stables, hotels, and restaurants, were visited. As a result of this inquiry the total losses for the city were estimated at $400oo,ooo yearly. A similar inquiry in Baltimore indicated that the annual losses in that city were about $700,o00. 200,000 IMEN ARE NOW WORKING SOLELY TO FEED TIHE RATS A more definite idea of the losses from rats may be gained by considering what it means in human effort. Taking the average yearly returns on a man's labor in agriculture, as shown by the census of 1910, it requires the con tinuous work of about 150,000 men, with farms, agricultural implements, and other equipment, to supply the foodstuffs destroyed annually by rats in the United States. In addition, rats destroy other property, mainly of agricultural origin, the production of which requires the work of about 50,000 men.