296 OHIO EXPERIMENT STATION: BULLETIN 332 



With the coming of the foHage it grows larger and thicker, and a 

 large conspicuous cottony mass is secreted among the waxy strands 

 of which are found the eggs. The formation of the egg-mass 

 causes the body of the female to become elevated so that it ulti- 

 mately sets at an angle. See Plate LII, Figs. 1 and 2, for illustra- 

 tions of the general appearance of the insect at this time. 



The male scale is much smaller, flat, and the male scale insect 

 is a delicate two-winged creature. 



The eggs are oval, light colored and slightly reddish-yellow. 

 The females deposit about 3,000 eggs each. 



Life history and habits. — The cottony maple scale passes the 

 winter as a small, flat, brown object secured to the twigs of the host. 

 Growth starts in early April ; the cottony mass is secreted and eggs 

 deposited in late May or early June. The eggs hatch in late June 

 or early July and the young establish themselves upon the leaves, 

 usually on the underside and along the midrib and veins. The males 

 become mature in August or September, fertilize the females and 

 perish. Before the foliage drops, the females migrate to the twigs 

 and establish themselves for the winter. 



Nature of work. — During the majority of seasons, the damage 

 created by this pest is not severe, but during occasional years the 

 insects appear in enormous quantities and great numbers of trees 

 may be killed outright. It is the opinion of Dr. S. A. Forbes, of 

 Illinois, that these destructive outbreaks may be expected to occur 

 about every 8 or 10 years in communities in which the insect be- 

 comes established. 



Food plants. — This pest is most destructive to soft maple and 

 basswood or linden. However, it can subsist upon a considerable 

 number of plants and may be considered as a destructive enemy to 

 some. The reported list is as follows : Norway maple, sugar maple, 

 Acer dasycarpum, box elder (Negmido negundo), osage orange, red 

 mulberry, Aralia japonica, apple, pear, alder, willow, hawthorn, 

 poplar, currant, lilac, grapevine, oak, hackberry, sycamore, rose, 

 currant, Euonymus, locust, sumac, beech, poison ivy, elm, poplar, 

 plum, peach, gooseberry and Virginia creeper. 



Distribution. — This insect abounds in the United States and 

 Canada, and is well known in Europe. It is stated by Sanders (44) 

 to be most destructive north of the 40th parallel, and that it is dis- 

 tinctly an Upper Austral zone species but occasionally reaches the 

 Transition zone. 



Natural enemies. — In July, 1916, large numbers of a lady-beetle, 

 Hyperaspis signata binotata Say appeared at Wooster and did per- 

 ceptible good, both as larvae and adults in destroying the cottony 



