164 



ASSOCIATION OF ECONOMIC ENTOMOLOGISTS. 



As long as the life histories of these insects remain incompletely 

 known no thoroughly practical method of extermination can be used. 

 It is true that the aphides can be profitably combated, but they can 

 be combated with a great deal more profit when that stage which con- 

 tains the least number of individuals is known. This stage is that in 

 which the true sexual forms occur, or when the first generation occurs, 

 which is from the egg. At these times the common methods of spraj T - 

 ing or fumigating can be used to eradicate instead of to combat, as 

 they are now used on unfavorable stages of the insect. 



In conclusion, some A T aluable aids in the study and description of 

 species of this family may be obtained from the following outlines 

 whenever a form is to be described. It will not only help to elimi- 

 nate mistakes by including all the main characteristics, but it will 

 also bring about an easy method of comparison of the same or differ- 

 ent species. Since it is not easy to completely describe a specimen 

 before it has been treated with clearing mixtures, it is necessary to 

 keep two kinds of notes, the one bearing on field notes and colorations, 

 the other on measurements and minute details. The investigator 

 should have about 200 of these keys for a season's work. The " color 

 key " should be printed on one side of a leaf and the " measure key " 

 on the other side. The " keys ' ' may then be arranged in the form of 

 a pad, 6 by 9 inches or other convenient size. 



Description Theme. 



Head 



[This key is followed when a final description is taken from the color and measure keys.] 



Color. 



Color and covering. 



Length of segments. 



e^Total length. 



Length in relation to the body. 



. [Shape. 

 Sensona <L T , , 



(Number per segment. 



fColor. 



Eyes | Ocular tubercles. 



bcelli. 



(Color. 

 Length. 

 Length in proportion to the body. 

 Color. 



Lateral tubercles. 

 Color. 



Color. 



fColor. 

 \ enation i„ 



Thorax 



Prothorax 



Meso-and Meta-thorax 



Wings 



[Normality, 



.,,. [Length. 

 Stigma <_, e ,.. 

 8 [Breadth. 



Total expansion. 



i Color. 

 Covering. 

 Normality. 



