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 susceptibility 

 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. Th< 

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

 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 ii 

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

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

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



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

 the scale covering in masses of a hundred or less. 



The newly-hatched young scale insects are minute, yellowis] 

 and crawl about freely. 



Life history and habits. The insect passes the winter in th( 

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

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

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

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

 continues; the sexes develop and mature. Later the eggs are d< 

 posited which constitute the over- wintering form. 



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

 the myriads of minute pumping insects so devitalizes it that whei 

 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 

 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. 



