SHADE TREE INSECTS 67 



The eggs, which are thin, flat, and oval, are deposited on the under side of 

 the leaf and slightly overlap each other somewhat like shingles. They are covered 

 with a brownish material which hardens soon after it is deposited. When first 

 deposited the egg is milky-white in color. 



The grub, or larva, grows to be about I4 inch long, is somewhat flattened, and 

 tapers slightly. When full grown it is yellowish-white, with legs, head, and 

 thoracic and anal shield black. The segmentation of the body is plainly marked. 

 Gubs live inside the mines which they excavate in the leaves. 



Life History. The beetles pass the winter in crevices of the bark and under 

 the litter on the forest floor. About the time the black locust leaves appear in the 

 spring, the beetles emerge and chew small oblong holes in the leaves. In a short 

 time the females lay their thin, flat, oval eggs on the lower surface of the leaves, 

 rarely more than five together. When these hatch, the tiny grubs, or larvae, 

 break through the under side of the eggs and eat their way into the leaf tissue. 

 At first the grubs from one egg mass will occupx' a single mine, but soon the 

 larvae emerge from this mine, wander to other leaves and construct new mines. 

 From that time on, each mine contains a single grub. The larva mines in several 

 leaves before reaching maturity, which usually takes about 3 weeks. Trans- 

 formation to the pupal stage takes place in the mine. The adults emerge about a 

 week later and feed on the lower surface of the lea\ es. There is probably but one 

 generation a year in northeastern United States. Two generations are reported to 

 occur in Ohio and other localities. 



Control. Shade and ornamental trees may be protected by spraying with lead 

 arsenate at the rate of 4 pounds Lo 100 gallons of water, with 2 pounds of flour or 

 1 pound of calcium caseinate as a sticking agent. This spray should be applied 

 in the spring as soon as there is sufficient foliage to retain it, in order to poison the 

 beetles as they begin to feed. 



The natural enemies of this insect often hold it in check for long periods of 

 time so that in general serious injury by this species is confined to local outbreaks. 



Two other closely related beetles may sometimes be found associated with the 

 locust leaf miner, Chalepits dor salts. They are C. nervosa Panz., and C. rubra 

 Weber. The adults resemble those of C. dorsalis but are slightly smaller and 

 neither has the central black stripe along the wing covers. They are seldom abun- 

 dant. C. nervosa apparently prefers dogwood, whereas C. rubra apparently prefers 

 basswood. 



Felt, E. P. N Y. State Mus. Mem. 8(2) :325-329. 1906. 

 Houser, J. S. Ohio .A.gr. Exp. Sta. Bui. 322:231-236. 1918. 



Birch Leaf Miner 



Fenusa puniila Klug 



This European species was first found in this countr}' in Connecticut in 1923 

 but was probably introduced some time before. Since then it has been found in 

 various localities in northeastern United States and southeastern Canada. Gray 

 birch, Betula populijolia; white, paper, or canoe birch, B. papyrifera; and the 

 European white birch, B. alba, are commonly attacked. Just how injurious this 

 insect will become is difficult to determine at the present time. The tiny larvae 

 e.xcavate blotchy mines in the tissues of the leaves, usually starting from near the 

 center of the blades. The affected parts become wrinkled and tuin brown, and if 

 the leaves are severely or entirely mined they fall from the tree. The terminal 

 leaves are most frec^uently injured. 



