COURTESY CONN. AGR. EXPT. STA. 
FIGURE 42.—Adults, larvae, and pupae of the imported willow leaf beetle, 
Plagiodera versicolora. Note skeletonization of leaves by larvae and holes 
eaten in leaves by adults. 
farther southward. Heavily infested trees may become entirely 
brown as early as mid-June. A considerable degree of natural 
control is exerted by the imported pupal parasite, Schizonotus 
sieboldi (Ratzeburg) (203). Extremely cold winters are also 
fatal to adults not well protected. . 
Systena marginalis (Ill.) feeds on oak in the midwest and on 
cypress in northern Florida and southern Georgia. The adult is 
dull pale yellow in color except for two black lines along the front 
margin of the elytra and a single black line along the hind margin. 
The wing covers are densely and coarsely punctate. Adults are 
present from mid-June to late August and feed by gouging out 
linear-shaped punctures in the leaves. This usually causes part or 
all of a cypress leaflet to turn red and die. The beetles occur in 
large swarms which tend to move about, spending only one to 
three days in any one place. A single swarm may encompass more 
than a dozen trees. 
Zengophora scutellaris Suffr., an introduced species, feeds on 
cottonwood and other poplars from New York and New Jersey to 
Montana and New Mexico. The adult is about 4 mm. long. The 
head, prothorax, and legs are yellow; the tarsal claws are toothed; 
there is a prominent tubercle on each side of the prothorax; the 
elytra are coarsely punctate; and the abdomen is black. The re- 
mainder of the body is yellow. Adults feed by skeletonizing the 
lower surfaces of leaves. The larvae feed singly in the soft inner 
tissues, chiefly against the upper surface of the leaf, making large 
black blotch mines. When they become full-grown they vacate 
their mines and drop to and enter the ground. Here they construct 
cells several inches below the surface in which to pupate. Trees 
heavily fed on by both larvae and adults may be completely 
defoliated. 
144 
