28 



ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47 



Control Measure 5 (end of circular) applied in late winter, or 

 Control Measure 3 applied after eggs have hatched and while 

 scales are still small. 



Putnam Scale, Aspidiotus ancylus (Putn.), fig. 21. — Ordi- 

 narily of little consequence, but a pest that may do serious dam- 

 age to elms following repeated foliar applications of DDT, Put- 

 nam scale sometimes encrusts limbs and branches, causing them 

 to die. Only about one-sixteenth inch in diameter, the female 

 scale covering is almost circular and is cemented to the bark 

 as a shell resembling an inverted saucer with a brick-red nipple 

 that contrasts with the dark gray or black remainder of the shell. 

 The shell of the male of the Putnam scale is oblong in shape. 



Fig. 22. — Elm leaf aphid: infestation on under side of elm leaf. The 

 aphids are greenish and of various sizes; some have wings and some are 

 wingless. 



