THE GLOOMY SCALE, AN IMPORTANT ENEMY OF 

 SHADE TREES IN NORTH CAROLINA. 



By Z. p. Metcalf. 



The gloomy scale is the most important insect enemy of shade 

 trees in North Carolina. We are led to make this statement for 

 two reasons : First, because it increases far more rapidly than 

 any other insect attacking shade trees, and in the second place 

 it is all but confined to the maples which have been so largely 

 used for shade purposes along the streets of our cities and towns. 

 The gloomy scale is rather closely related to the famous San 

 Jose scale, which is so destructive to our fruit trees. Unlike 

 the San Jose scale it is a native insect. We are led to believe 

 this because the gloomy scale is very heavily parasitized, indi- 

 cating that it has been established in this country for a long 

 period of time. Then the fact that the scale has been found on 

 a willow along a stream in Lincoln County is another very strong 

 indication of its nativity. 



The gloomy scale differs from the San Jose scale in another 

 very vital respect, and that is that it is very much more difficult 

 to control. We believe that this is due to the fact that the 

 gloomy scale lives over the winter as a mature insect, while the 

 San Jose scale lives over the winter as a half grown young. The 

 latter condition enables us to apply very caustic insecticides at 

 a time when the insect is weakest, and at the same time the tree 

 is in a dormant condition so that it is not injured in the least. 

 Then, too, the dorsal scale of the gloomy scale is much thicker 

 and more closely applied to the ventral scale than is the case 

 with the San Jose scale, so that the gloomy scale is especially 

 well protected against any contact insecticide. 



These facts forced themselves upon our attention soon after 

 we commenced experiments for the control of this insect four 

 years ago. We soon discovered that the remedies usually recom- 

 mended for the San Jose scale would be of little or no use 

 against this insect. As a matter of fact the mortality of the 

 scale on some unsprayed trees was less than that of some trees 



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