58 RODENTS OF IOWA 



The foundations of floors and buildings are in some instances un- 

 dermined by rats, thus causing the structures to sag or to fall. 

 Unsightly holes in uncemented cellar floors and walls usually indi- 

 cate the presence of these pests. The corners of doors and of boxes 

 containing stored materials are eaten away; and even artificial 

 ponds and embankments may be ruined by the numerous burrows 

 of the animals. 



Rats are also objectionable from an hygienic point of view and 

 are known or suspected to be the transmitters of several diseases. 



It is believed that rats are responsible for the presence of human 

 plague in a community, and also that they frequently carry the dis- 

 ease from one locality to another. Bat leprosy is not an uncommon 

 disease among these animals and is of interest because of its similar- 

 ity to that disease in man. In March, 1917/T. T. Job of the 

 Department of Animal Biology of the State University came upon 

 a specimen bearing this disease. The rat was collected in one of 

 Iowa City's livery stables. 



A number of species of internal parasites are harbored by rats 

 and mice, and some of these parasites bear a close relation to certain 

 diseases of man. The disease known as trichinosis,, due to the 

 presence in the body of minute parasitic worms called trichinae or 

 flesh-worms, is most frequently carried by rats and mice and prob- 

 ably will never be entirely eradicated from man until these rodents 

 themselves have been exterminated. For this reason rats that have 

 been killed or trapped should never be fed to swine, but the bodies 

 should be buried or burned. 



Natural Enemies. To the all too widespread desire for the kill- 

 ing off of birds and other animals which habitually prey on de- 

 structive rodents, rats and mice included, the great increase in the 

 number of such pests is largely due. ' * The value of carnivorous 

 mammals and the larger birds of prey in destroying rats and mice 

 should be more fully recognized, especially by the farmer and game 

 preserver. Rats actually destroy more poultry and game, both eggs 

 and young chicks, than all the birds and wild mammals combined ; 

 yet some of their enemies among our most useful birds of prey and 

 carnivorous mammals are persecuted almost to the point of ex- 

 tinction. An enlightened public sentiment should cause the repeal 

 of all bounties on these animals and afford protection to the ma- 

 jority of them. ' ' 8 Greater care should be exercised in discriminating 



8 Lantz, D. E.. House Rats and Mice: U. S. Dept. Agr., Bur. Biol. Surv. 

 Farmers' Bull. 896, 20, 1917. 



