TRANSACTIONS HURTICULTURAL SOCIETY OF NORTHERN ILL. 353 



insects are seldom recognized in their perfect state by those unacquainted 

 with their history, especially those species which are shy, hidini,^ during 

 the day (as the Sa/>t'n/ii) and coming forth only at evening. 



In order to ascertain the most vulnerable point in an insect's history, 

 we must be thoroughly acquainted with its entire life, from the moment 

 the egg is deposited until the close of its existence in the perfect state. 

 If we find this point to be the egg state, on account of the situation 

 selected, exposed condition, aggregation, or other cause, then, as a mat- 

 ter of course, it is against this state that our efforts should be directed; 

 and the same is true with reference to any other stage of their life which 

 may be found to present the most vulnerable point. 



By understanding these things in reference to our various injurious 

 insects we are enabled to group together, to a certain extent, those of 

 similar habits, and presenting the same vulnerable point, and thus gener- 

 alize remedies ; and if we can find a method of culture which is also at 

 the same time a remedy, we are thus enabled to make a given amount of 

 labor answer a double purpose. 



This grouping of habits does not necessarily correspond with the 

 grouping in the classification of insects; in fact, it may, and often will, 

 bring together insects widely differing from each other. 



As an illustration, I may mention the Saperda, JEgcria exitiosa (peach- 

 root borer), and a species of woolly aphis — species belonging to three dif- 

 ferent orders — which operate more or less about the collar, or lower part 

 of the trunk, of fruit trees; if we can find a method of mulching, or, to 

 use a more general term, of cultivating this part of the tree, which will 

 operate as a protection against these species, and at the same time 

 be beneficial to the trees, an important point is gained ; and, although 

 it may not do away entirely with the necessity of special remedies to 

 these different species, yet by steadily persevering in it we constantly 

 diminish our insect foes, and render the special remedies less and less 

 necessary. 



But, as heretofore stated, in order to direct our experiments intelli- 

 gently, it is necessary to know something in reference to these insects in 

 their different stages. As we meet with the borers, when at work, almost 

 exclusively in the larval state, it is important to ascertain whether they 

 possess any characters in this state by which we may determine what they 

 will be in the perfect state, and thus be enabled to trace their habits in 

 that state, and see whether it presents any vulnerable point. 



As a general rule it is e.xceedingly difficult to determine species in 

 this stage of their existence; still there are ( iiaracters by which we may, 

 at least, approximate this in reference to the borers, and ascertain the 

 group to which the respective larvae belong, and thus gain a pretty correct 

 idea of their habits in the other stages of their lives. 



As the first step in grouping them by their larval characters, we may 

 separate them in two divisions, thus : i. Those possessing feet ; 2. Those 

 which are footless grubs. 



The first division maybe again divided into two sections, thus: 

 I. Those having but six feet or legs, which are true legs, terminating in a 



