282 ANNUAL REPOET 



It has been calculated that on an average there are at least five spe- 

 cies of insects that prove to be more or less injurious to each species 

 of plant. The actual number will probably be somewhat larger, as 

 the number of newly discovered insects has increased unexpectedly 

 during the latter half of the present century. As soon as a plant 

 therefore will increase under some favorable circumstances so as to 

 exceed the proper bounds, these insects that prey upon it will also be 

 favored by such an increase of food-plants, and will soon appear in 

 a proportionately large number and check this undue increase of the 

 plant. 



While thus a large class of insects are occupied as scavengers on land 

 and in water, and a still greater number to produce a healthy and lux- 

 uriant growth of vegetation, or to check an undue increase; not a small 

 class are occupied in keeping the increase of these insects themselves 

 within proper bounds, by preying upon them. A large class are directly 

 carnivorous, the tigers and lions among insects, by preying upon every 

 insect that comes in their way; another and more important class to 

 man are parasites on other insects, their larvaB or eggs which they de- 

 stroy. Thus the balance of nature is ever kept up, and this law is 

 most beautifully exemplified in the case of insects. 



GOOD AND BAD INSECTS. 



Insects are moreover of importance as an article of commerce. Not 

 only does the honey bee supply us with a delicious and healthy food, 

 the cochineal insect with a magnificent coloring matter, but many 

 other important products come directly or indirectly from insects, as 

 shalac and silk the value of which amounts to millions annually. In- 

 sects come in more or less relation to man in almost every branch of 

 industry with which we are acquainted. 



That relation in which they attract the greatest attention is 

 undoubtedly as injurious to our crops, and as this involves a loss of 

 millions upon millions annually to our country, and to the individual 

 often the greater part of his profit for the j^ear, if not more, it is a 

 question well worth our attention. This is applied entomology, and 

 if time would allow it would be a profitable thing to stop just here and 

 try to make it clear to all of us in what this relation consists, and to 

 what extent the evil might be reduced. This is an evil, if we so 

 must call it. which can never be altogether done away with, and 

 which would not even be desirable under the present condition of 

 things; but it can be reduced to a minimum, and this applied to a sin- 

 gle crop of our State — the wheat crop — would make a difference of 

 several millions annually in our favor. 



