56 



ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47 



overwinter under the shell of the female, hatch in the early sum- 

 mer. Each nymph or crawler moves to a new place, settles after 

 a few days, and inserts its beak into the leaf tissue to feed. It 

 soon begins to make a shell. This species of scale produces two 

 broods of crawlers during the summer. 



Fig. 41. — Pine bark aphid: infestation on white pine. The aphid s them- 

 selves are inconspicuous, but an infestation is easily recognized by the 

 splotches of cottony substance they produce. 



