58 OUR SHADE TREES AND THEIR INSECT DEFOLIATORS. 
Moreover, whole rows of old Silver-leaved Poplars (Populus alba), more 
than 1,500 in all, were cut down during the winter of 1887-88, and their 
places filled by young Red Oaks, Sugar Maples, and Silver Maples. 
Many of the Box Elders were also taken down, although these were in 
the main young trees. A number of old tree boxes were removed, and 
where the tree was large enough to stand up by itself and simply needed 
protection from horses, a coarse wire screen was substituted for the 
box with good effect. 
