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ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47 



ing shock — may indicate that the roots have been eaten by the 

 white, legless, crescent-shaped grubs of the black vine weevil. 

 The grubs feed on plant roots from late summer until late spring. 

 Development and transformation of this insect take place in the 

 soil, and the adult weevils make their way to the surface about 

 the first of June. The adults are seldom observed, as they hide 

 during most of the daylight hours and feed sparingly, mainly at 

 night, on the foliage toward the center of the plant. The female 

 does not deposit her eggs on a plant, as many insects do, but 

 simply drops them on the ground. This insect has only one gen- 

 eration a year. A long preoviposition period makes it possible to 

 time a control spray to kill all adults after they have emerged 

 from the soil and before they have dropped eggs. 



Fig. 49. — Black vine weevil: larvae and damage to small yews. The 

 adult, a black snout beetle, is seldom seen. 



