THE PARASITES OF MAN. 45 



simply the carriers of tbe parasites; others live upon surplus 

 food or upon food not entirely consumed by their hosts; still 

 others make use of the host himself, by eating part of the 

 same; and a few not satisfied with being such contemptible 

 beings, commit even murder by enfeebling and killing the 

 host that provided them with food and shelter. 



Farmers have to fight almost constantly against all 

 kinds of parasites, since otherwise their hopes of rich returns 

 for their labors in the fields would come to naught. And vet 

 how few^ farmers realize how much they lose year after year 

 iDy the inroads of such pilfering beings, simply because these 

 live a hidden life not easily observed. They, with other ene- 

 mies such as plant-eating insects, take every year the lion's 

 share of our crops, and some vegetable parasites, such as 

 rusts, smuts, and similar lowly organized plants, not infre- 

 quently destroy all the plants so carefully planted and culti- 

 vated by the farmer. Some still smaller parasites, as certain 

 kinds of bacteria, cause diseases among man and domesti- 

 cated animals, and frequently to such an extent that they 

 are swept av^^^ayor decimated over a large area. Other para- 

 sites live inside man and his two or four-footed friends, and 

 cause great losses, by weakening or even killing them. Still 

 others, less dangerous but equally annoying, and in extreme 

 cases as bad, live upon the various kinds of domesticated 

 animals, and cause all sorts of trouble and diseases. And 

 even man, the crov^n of creation, is not entirely immune; 

 even he, not excepting her, has been seen — in other States of 

 course — to scratch himself, or to investigate with great in- 

 dustry the heads of her promising offspring. 



All parasites dwell either upon the bodies of their hosts 

 or inside of them, for a short time or permanently, and as 

 they subsist upon substances of great and even vital import- 

 ance to the latter they cause more or less serious disturb- 

 ances, even fatal diseases. Such parasites belong either to 

 the vegetable or to the animal kingdom. It is not the in- 

 tention to discuss the former, or all of the latter, as being 

 foreign to an entomological report. Only such parasites will 

 be discussed as are either genuine insects, or so closely allied 

 to them as to be usually considered as such. Thev will be 



