31 



BULLETIN OF 

 MASSACHUSETTS BOARD OF AGRICULTUEE. 



THREE COMMON ORCHARD SCALES.*' 



By Prof. H. T. Fbrnald, Prof etnor of Entomology, Ma»*achxiBeUa Agricultural 



College. 



Our knowledge of scale insects has been very limited until 

 recently. The injuries they cause have passed unnoticed in most 

 cases, while the occasional loss of some tree has too often been 

 attributed to some other cause. The appearance of the San Jos6 

 scale in Massachusetts, however, and its rapid extension over the 

 State, followed everywhere by serious injury to the trees attacked, 

 has attracted much attention to this group of insects. 



Although over a hundred different kinds of scale insects prob- 

 ably occur in Massachusetts, only three are likely to be present 

 in any orchard in sufficient abundance to cause injury to the trees 

 and demand attention, and only one of these is usually so destruc- 

 tive as to require radical measures for its control. These three 

 are the oyster-shell scale, the scurfy scale and the San Jose scale. 

 It is important that every person having fruit trees should learn 

 to recognize these three scales, and know what treatment to apply 

 for each if he wishes to obtain his crops, or, in case of the San 

 Jo86 scale, if he wishes even to keep his trees alive. 



The Oyster-shell Scale. 

 {Mytilaspis pomorum Bouch6.) 



This scale is a native of Europe, and reached this country, 

 where it is now generally distributed, about a hundred years ago. 

 It is probably present in every orchard in Massachusetts in greater 

 or less numbers, and is also abundant on many of our shade and 

 forest trees. 



During the winter the scales of this insect are very noticeable 

 on the twigs and smaller branches of many trees, often com- 

 pletely covering them. The scale is about one-eightli of an inch 

 long, quite pointed at one end, rounded at the other, and usually 

 somewhat curved to one side (Fig. 1) so that in general outline 

 it somewhat resembles an oyster shell. Its color is dark reddish 



• Reprinted from Crop Report for May, 1901. 



