2 



THE OYSTER-SHELL SCALE. 



(Lepidosaphcs ulmi L.) 



ORIGIN AND DISTRIBUTION. 



The origin of the oyster-sliell scale is a matter of some uncertainty. 

 It has a world-wide distribution, and was introduced into the New 

 England colonies at an early date. The first American account of this 

 pest was written by Enoch Perley in 1794, in which he stated that it 

 was doing considerable damage to the apple in Cumberland County, 

 Maine. In the early sixties it had reached the Mississippi River, and 

 at the present writing (April, 1910) occurs in every State of the Union 

 with the possible exception of South Dakota, Oklahoma, and Texas. 

 Its occurrence in these States is practically certain, but there appear 

 to be no records in literature to this effect, and it has not been received 

 from these States by the Bureau of Entomology. The insect is very 

 troublesome in the Northern States and is especially common in the 

 New England States and those bordering the Great Lakes. 



DESCRIPTION AND LIFE HISTORY. 



This insect has received the common name "oyster-shell scale," 

 owing to the resemblance of its scale or covering to a long, narrow 

 oyster shell, as may be seen by reference to figure 1. The adult 

 female scales are about one-eighth of an inch in length, usually brown 

 to dark brown in color, though occasionally they have a grayish 

 appearance which is due to bleaching over winter. If present in 

 large numbers, for want of room they assume various more or less 

 curved shapes. The scale of the male in shape and color resembles 

 that of the female, but is smaller and possesses at the posterior 

 extremity a small hinge or flap which permits the exit of the adult 

 male. 



If during winter or early spring one of the female scales be removed, 

 numerous small, oval, white eggs varying in number from 40 to 100 

 will be revealed, and at the anterior portion can be seen the dead and 

 shriveled body of the female. 



In Canada and the Northern States there is thought to be but one 

 full brood annually, whereas in the Middle and Southern States the 

 species is double brooded.^ 



The following records from literature and from the Bureau of Ento- 

 mology will indicate the time in the spring of hatching of the eggs of 

 this insect, in various localities. This time will, of course, vary with 

 the season, but, in general, as long ago stated by Doctor Mygatt, in 

 Illinois, will for any locality be shortly after the time of the falling 

 of the blossoms of the apple. 



[Cir. 121] 



