76 



INSECT LIFE. 



species are the green ones that are very abundant 

 some years on the tips of branches of apple, and the 

 dark-colored ones that cause the leaves of peach and 

 cherry to curl, thus forming- tubes within which they 

 live. 



Find a colony of aphids in a convenient place 

 where they can be observed from day to day, take 

 notes on their habits and structure, and finally write 

 an account of what you have learned. The following 

 suggestions will aid you in this study : — 



1. Observe the form of the body. Usually there 

 are two forms of individuals in a colony — one wing- 

 less, the other winged. Usually the greater num- 

 ber of individuals are w^ingless, and these never 

 develop wings. But as aphids increase in numbers 

 very rapidly, there is danger of the destruction of 

 the food-plant and a consequent destruction of the 

 colony. To avoid this danger, from time to time 

 individuals are born that develop wings. These fly 

 away, and start new colonies in fresh localities. The 

 nymphs of the winged form can be recognized by 

 their wing-pads. 



2. Observe the reproduction of aphids. Both 

 the wingless and the winged forms referred to 

 in the preceding paragraph give birth to living 

 young. In some species the young aphid pro- 

 duced in this way is inclosed in a soft shell, but 

 usually not. The birth of the young aphids can be 

 easily seen with a hand lens at any time during 

 the warmer part of the year in almost any colony of 

 aphids. 



3. The two forms of aphids that are being consid- 

 ered now consist each of a single sex, all of the indi- 



