286 OHIO EXPERIMENT STATION: BULLETIN 332 



pest, the present one is much more prevalent and destructive as a 

 shade tree and forest insect, on account of the high susceptibihty 

 of a number of native trees and shrubs to its attacks. Indeed, it 

 may be classed as the most destructive shade tree and forest scale 

 insect in the State. 



Description. — As the name indicates, this scale insect resem- 

 bles a miniature oyster shell. It is pointed at one end, and gradually 

 increases in width, the opposite end being broad and rounded. The 

 scale varies of course according to the condition and species of the 

 host, but generally the female is from one-tenth to one-eighth 

 of an inch in length and the male about one-sixteenth of an inch in 

 length. The mature female scale insect is sacklike and devoid of 

 appendages, while the mature male is winged. (See Plate XLVIII, 

 Fig. 1, for an idea of the general appearance of the scale.) 



The eggs are oval, pearly-white in color and are found beneath 

 the scale covering in masses of a hundred or less. 



The newly-hatched young scale insects are minute, yellowish 

 and crawl about freely. 



Life history and habits. — The insect passes the winter in the 

 egg stage, well protected by the securely cemented down scale of 

 the mother. By mid-May or early June, the eggs hatch and the 

 young, after a short period of wandering, settle on the bark and 

 commence sucking the sap. The scale is then formed. Growth 

 continues; the sexes develop and mature. Later the eggs are de- 

 posited which constitute the over-wintering form. 



Nature of work. — The robbing of the host of its sap supply by 

 the myriads of minute pumping insects so devitalizes it that where 

 the infestation is severe the plant may be killed outright or at 

 least parts of it perish. 



It is no uncommon sight to find susceptible hosts both under 

 city and country conditions dead as the result of the work of this 

 species. In some instances which have come to the writer's atten- 

 tion entire woodlots of ash have been cut prematurely on account 

 of the threatened total destruction by it. (See Plate VI.) 



Under city conditions the injury is sometimes severe and ex- 

 tended, the more susceptible hosts being killed outright by it. 



Food plants. — Quaintance and Sasscer (40) record a list of 

 ninety-nine plants upon which this scale is known to occur. In 

 Ohio the more common hosts, named somewhat in the order of their 

 susceptibility are as follows: Carolina and lombardy poplar, lilac, 

 horse chestnut, buckeye, ash, cottonwood, willows, apple, red-twig 

 dogwood, etc. 



