INSECT PESTS'OF OHIO SHADE AND FOREST TREES 307 



living scale insects. The scale of this species is slightly convex and 

 of a circular outline, measuring about one-sixteenth of an inch in 

 diameter. 



Life history and habits. On May 11, 1915, the writer observed 

 the young just beginning to appear at Cincinnati, Ohio. Beneath 

 the upper scale surface of the female was found a mixture of eggs, 

 quiescent young and active young. Apparently, the young remain 

 inactive a little while after hatching and later make their way from 

 beneath the rear tip of the waxy scale mass. The number of eggs, 

 quiescent young and active young appeared to be about 50 for each 

 female insect. On July 19, 1907, the newly-emerged young were 

 observed in quantity at Cleveland, Ohio, so there seems to be con- 

 siderable latitude in Ohio as to the time of the appearance of the 

 young. It is supposed that there is but one brood of young per 

 season in Ohio, but this fact is not definitely known. 



Upon emerging the young establish themselves and begin work. 

 The lower branches of the host as a rule are more severely infested 

 than the upper ones. 



Nature of work. The pit-making oak scale is one of the more 

 destructive scales of oak when it once becomes established. Large 

 as well as small trees are killed outright. Badly-infested trees 

 present a ragged appearance and the dead brown leaves hanging 

 to the dead branches are particularly noticeable and unattractive. 

 (See Plate LVI, Fig. 2.) 



Food plants. The writer has taken the pit-making oak scale on 

 English oak (Quercus robur), white oak (Q. alba) and a pyramidal 

 oak, the species of which he does not know. Other workers have 

 reported it upon white swamp oak (Q. platinoides) , a golden oak 

 (Q. glandulifera) and Q. sessiflora. 



Distribution. The pit-making oak scale has been reported from 

 the following localities in Ohio : Mentor, Glendale, Edge water Park, 

 (Cleveland) , and numerous places in the parks and on the streets of 

 Cincinnati. Outside of Ohio it is known to occur in Europe, Canada, 

 Massachusetts, Connecticut, New York, District of Columbia, Penn- 

 sylvania, Michigan, Maryland, New Jersey, Virginia, North Caro- 

 lina and California. Special attention should be drawn to the preva- 

 lence of this scale in the Cincinnati district. There it is well 

 distributed through the parks of the city and occurs on street trees 

 as well, sometimes killing large oaks 35 to 40 feet in height. 



Natural enemies. A small hymenopteron, Habrolepis dal- 

 manni Westw., has been reported as parasitic on this species in 

 this country; and two birds, the blue tit and the long-tailed tit, 

 have been reported from England as feeding upon it. 



