mine, or they vacate it and pupate in the ground. There is considerable literature on 
this family (53, 723, 724, 725, 1289). 
The cottonwood leaf beetle, Chrysomela scripta F., occurs throughout the 
United States and Canada and feeds on the leaves of poplar, willow, and alder. 
Adults are about 6 mm long. The head and thorax are black and the margins of the 
thorax are yellow or red. The wing covers usually are yellowish with black stripes, 
but are sometimes almost pure golden to black. Mature larvae are blackish and 
about 12 mm long. There are two whitish spots on each side. They are located at the 
site of the scent glands, one on each side of each segment except those on the 
prothorax and the last two on the abdomen. The scent glands emit a pungent odor 
when the larvae are disturbed. 
Winter is spent in the adult stage under loose bark or debris or in clumps of grass. 
Emergence begins in early spring and the adults feed on unfolding leaves or on 
tender bark at the tips of twigs (528). Eggs are deposited in groups of 15 to 75 on 
the undersides of leaves. The young larvae are gregarious and, feeding side by side, 
skeletonize the leaves. Later, they feed separately and consume the entire leaf, 
except the larger veins. At maturity they attach themselves to leaf surfaces, the 
bark, or to weeds and grass beneath the trees to pupate. There are several genera- 
tions per year. Severe infestations occur occasionally and cause considerable 
damage. 
The aspen leaf beetle, C. crotchi Brown, and C. interrupta F. occur commonly 
throughout the Eastern States. The adults and larvae of C. crotchi feed on poplar 
(1093); those of C. interrupta feed on the leaves and at times on the tender bark of 
alder. C. knabi Brown feeds on poplar in the Northeastern States. It has also been 
observed feeding on willow in Tennessee. 
The elm leaf beetle, Pyrrhalta luteola (Miller), an introduced species first: 
recorded in North America at Baltimore, Md., well over a century ago, now occurs 
throughout most of the United States (fig. 111). Its hosts are all species of elm. In 
the Northeastern States, American elm is often severely attacked and seriously 
damaged. Farther west, Siberian elm is also frequently heavily attacked. European 
elms are especially subject to injury. Adults are about 6 mm long and yellowish to 
dull green, with a black stripe along the sides of the wing covers. There is also a 
short, dark spot at the base of each wing cover. Full-grown larvae are dull yellow, 
with two rows of black spots on the dorsum, and are about 12 mm long. The head, 
legs, and tubercles are black and there is a broad, yellow stripe down the middle of 
the dorsum. Pupae are bright orange-yellow with a few black bristles and they are 
about 5 mm long. 
Elm leaf beetles spend the winter in sheltered dry places. In the Northeastern 
States most of them hibernate in house attics, barns, and sheds. During periods of 
warm weather in the winter many of these beetles become active and cause 
considerable annoyance by crawling into living quarters or onto windows. Spring 
emergence begins about the time the buds of elm begin to swell, and the adults fly 
to nearby elms and feed by chewing holes in the unfolding leaves. Egg laying 
begins in late May or early June, each female laying from 400 to 800 eggs (/223, 
1264). Hatching begins in about | week and the larvae feed for 2 or 3 weeks on the 
undersurfaces of the leaves. Only the veins and upper surfaces are left, and the 
leaves soon dry out and turn brown. Full-grown larvae crawl down the tree and 
pupate in bark crevices or at the base of the tree. In the Eastern United States there 
may be one or two complete generations and a partial third. Usually the first 
260 
