ABOUT KEYS. 



Such keys as are given here are, for the 



Keys . ~. . ,. , 



most part, simplified versions of keys in 

 special, more technical, books and papers. They have 

 been simplified in two ways: by leaving out forms which 

 are not very likely to attract the notice of beginners or 

 whose separation involves too great technicalities, and by 

 using, as far as possible, easily appreciated characters 

 even though they may not be, otherwise, the best charac- 

 ters to use. The result of the first simplification is that 

 forms will be found which do not fit anything in the key 

 although they may come close to it. An attempt has been 

 made to word the keys so that forms which were not 

 intended to be included will not fit anywhere, thus avoid- 

 ing a misidentification. This attempt has not always 

 been completely successful, especially for southern and 

 west-of-the-Mississippi forms. Working a key backward, 

 from the name to the start, usually gives so good a de- 

 scription of the form in question that it is not further 

 described in the text. 



Start at I and decide which of the two 

 How to Use a ^ Qr more ) alternatives best agrees with the 

 specimen; then go to the number indicated 

 at the right; continue this process until a name without a 

 following number is reached. Do not take too much for 

 granted. If a thing is said in one alternative to be black, 

 it is not necessarily not black in the other unless this is 

 definitely stated. If you reach a point where neither 

 alternative fits, go back to the place where you had most 

 doubt concerning a choice and take the other alternative; 

 perhaps the statements were not sufficiently clear and you 

 made a wrong choice. If nothing works, it would be 

 kind of you to conclude that you have a species which was 

 not included in the key, although the fact of the matter is 

 that it is next to impossible to draw up a relatively simple 

 key which will not sometimes stick in the lock. 



THE CONTROL OF INJURIOUS INSECTS 



This section may seem out of place in a Field Book, 

 but the garden is a part of the "field" as far as insects are 



27 



