INSECT PESTS OF OHIO SHADE AND FOREST TREES 305 



its limitations because of the necessary repetition. In some in- 

 stances where unusual facilities exist for drenching, this control 

 method has considerable merit. 



THE BURR OAK KERMES 

 (Kerm.es pubescens Bogue) 



Description. This insect might appropriately be called the oak 

 leaf -crinkling kermes because of the peculiar distorting effect it has 

 upon the leaves of the host, which will be described later. (See 

 Plate LV, Fig. 2.) This is one of the fleshy scale insects, and is not 

 covered with a protecting shield or cover. 



The adult female is almost globular, although slightly longer 

 than broad and is about one-eighth of of an inch long. (See Plate 

 LV, Fig. 2.) They are found in greatest abundance upon the 

 smaller twigs, leaf petioles and midribs. Clothing the body of the 

 female is a downy pubescence, and it is due to this material that the 

 species was given its specific name pubescens. When this pubes- 

 cence is rubbed off, the derm or surface appears shiny and is beauti- 

 fully marked with dark and light brown mottlings, the darker por- 

 tions of which assume more or less distinct lines, one median line 

 extending lengthwise and this crossed at right angles by two or 

 three others of a similar nature. When the females are removed 

 from the host, a distinct white patch remains. 



The young are red, mite-like, six-legged, crawling creatures. 



The males emerge from tiny white cocoons which are located 

 mainly upon the underside of the twigs and branches. They are 

 delicate reddish-hued creatures having two long filaments extending 

 backwards. 



Life history and habits. The partly-grown females pass the 

 winter in the shelter of crevices in the bark of the host. From 

 these retreats they emerge in the following spring at the time foli- 

 age development starts and establish themselves upon the tender 

 twig tips, leaf petioles, leaf midribs and veins. The majority are 

 found upon the leaves. Leaf distortion commences almost simul- 

 taneously with the establishment of the scale insects and as the 

 insects develop in size the supporting leaf becomes more and more 

 distorted. 



By mid-May during the time the burr oaks are in blossom, the 

 males leave their cocoons. The process of emergence is .curious. 

 First, the white filaments appear at the tip of the cocoon ; next, the 

 tip of the abdomen and lastly the head. The insect becomes quite 

 active, orients itself, and seeks seclusion in the crevices of the bark 

 of the host. When disturbed it takes flight. By August 1 in the 

 vicinity of Cincinnati, the young have been produced, but the bodies 



