ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 5 



Cynthia Moth, Samia cynthia (Druiy). — The 3-inch, green 

 caterpillar of this species has black dots and blue tubercles on 

 its back. It feeds on the leaves of the tree of heaven. The adults 

 are handsome brown moths, each with a wingspread of 6 to 8 

 inches. Sometimes caterpillars of this kind defoliate the trees 

 on which they feed. 



Control Measure 1 or 2 (end of circular) while small cater- 

 pillars are feeding. 



ARBORVITAE 



Bagworm, Thyridopteryx ephemeraeformis (Haw.), fig. 2. 

 — A widely distributed common pest, the larva of this species 

 feeds ravenously on both evergreen and deciduous trees and 



Fig. 2. — Bagworm: cares or bags constructed by larvae. Some of the 

 bags shown here are almost filled with eggs laid by adult females of the 

 bagworm. Eggs that survive the winter hatch in early summer. The ap- 

 pearance of bags varies with the kinds of leaves from which the larvae have 

 made them. 



shrubs. Usually evergreens defoliated by bagworms d'e. Some 

 of the spindle-shaped bags hanging from trees and shrubs dur- 

 ing the winter contain eggs that produce a crop of worms in the 

 following spring or summer. In southern Illinois, these eggs 

 hatch usually during the latter part of May, in central Illinois 

 during the first part of June, and in northern Illinois during the 

 latter part of June. Newly hatched larvae are easily overlooked. 

 After leaving the mother bag, a small larva feeds on nearby 

 foliage and begins to build a tough bag for itself with silken 



