REPORT OF THE ENTOMOLOGIST. 185 



may render oar homes untenable. They burrow within our house- 

 hold and agricultural implements. They occasionally take possession 

 of our books. No asylum is so secure that they may not intrude; no 

 condition in life is exempt from their presence and attack." 



There is scarcely a plant that grows, whether cultivated or wild, but 

 that affords food and shelter to one or more species of insects. It is 

 to the vegetable world that they are mainly indebted for their suste- 

 nance; and it has been estimated that there are, upon an average, six 

 species of insects attacking each species of plant. Of course, upon 

 our cultivated plants, such as garden vegetables, shrubs, trees, grasses, 

 grains, etc., the number is much greater. In Europe, where the study 

 of insect depredations has received much more attention than it has 

 here in the United States, it has been ascertained that at least 537 

 distinct species are injurious to the oak, 107 to the elms, 264 to the 

 poplars, and 396 to the willows; while the conifers afford a livelihood 

 to 332 species. These insects, when they become more numerous than 

 ordinarily, must of a necessity damage the particular plants upon 

 which they work or feed ; and, when very numerous, cause them not 

 only to become dwarfed and sickly, but in many instances even to die. 



By carefully investigating the subject of insect injuries to any spe- 

 cial crop or plant in some particular region, the result is most startling. 

 Professor Riley, who is certainly in a position to give us the most ac- 

 curate figures attainable, in writing upon this feature of the subject, 

 says: "The losses occasioned by insects injurious to agriculture in the 

 United States are, in the aggregate, enormous, and have been variously 

 estimated at from $300,000,000 to $400,000,000 annually." 



If approximately truthful estimates could be had of the pecuniary 

 losses resulting from insect depredations on each of our principal 

 crops, the figures obtained would be sufficient arguments to show the 

 importance of investigations toward their prevention. Perhaps not 

 a single crop that is cultivated escapes without an average annual loss 

 of at least one-tenth from this cause — an amount of injury which 

 would be hardly noticed; but when the injury amounts to as much as 

 one-fourth or one-half, the loss becomes much more apparent. Occa- 

 sionally, however, the entire crop is destroyed. If we put this loss 

 occasioned by insect depredations in the form of a direct tax that is 

 levied and collected annually without the least show of resistance on 

 our part, the matter assumes a more serious aspect. Yet this is really 



