gregariously, whereas leaf mining larvae usually feed singly, each 
within its own mine. Adult feeding is characterized by the pres- 
ence of holes eaten all the way through the leaf, or by skeletoni- 
zation usually of the lower surface of the leaf. Free-living larvae 
elther fasten themselves to the surface of a leaf to pupate, or move 
to the ground to do so. Leaf mining larvae pupate either within 
the mine, or they vacate it and pupate in the ground. This family 
has been treated by Leng (451), Leng & Mutchler (452, 453), and 
Wilcox (264). A few of the more common eastern species are 
discussed. 
The cottonwoed 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 yel- 
low 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. Eggs are deposited in groups of 15 to 75 eggs each on the 
undersides of leaves. The young larvae are gregarious and, feed- 
ing side by side, skeletonize the leaves. Later, they feed separately 
and consume the entire leaf, excepting the larger veins. At ma- 
turity they attach themselves to leaf surfaces, the bark, or to 
weeds and grass beneath the trees to pupate. There are several 
generations per year. Severe infestations occur occasionally and 
cause considerable damage. 
Chrysomela interrupta F. and C. crotcht Brown occur commonly 
throughout the Eastern States. The adults and larvae of inter- 
rupta feed on the leaves and at times on the tender bark of alder; 
adults and larvae of crotchi feed on poplar. 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 (Mueller) (fig. 40), an 
introduced species first recorded in North America at Baltimore, 
Md. well over a century ago, now occurs throughout most of the 
United States. Its hosts are all species of elm. Irn the Northeastern 
States, American elm is often severely attacked and seriously 
damaged. Farther west, Chinese 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 the 
pupae are about 5 mm. long. 
138 
