40 PRACTICAL ZOOLOGY 



country. Incidentally, this study was part of a series of studies, 

 which led to a cure for hydrophobia. 



LEOPARD MOTH. - - The caterpillar of another moth, the 

 leopard moth (Fig. 27), is an important shade- tree pest, but with 

 very different habits from those of the gypsy moth. The leopard 

 moth was also introduced from Europe. Both the adults and 

 larvae are spotted like a leopard. The male moth (Fig. 27, B) 

 expands a little more than an inch and the female (Fig. 27, A) 

 over two inches. The larvae, which are about two inches long 

 (Fig. 27, C), burrow into the wood of trees that are weakened by 

 the weather or by some other insect. Serious attacks can be 

 prevented by digging out the boring caterpillars as soon as they 

 appear, or by collecting the adults as they congregate in the 

 evening beneath electric street lights. 



OTHER SHADE-TREE PESTS. A few of the multitudes of 

 shade-tree insects are the elm-leaf beetle, the elm-bark louse, tent 

 caterpillars, fall webworm, elm, maple, and locust borers, and 

 cottony maple scale. Certain trees are less liable to attack than 

 others. For example, the tulip tree and the hardy catalpa are 

 practically immune from insect injury; oak trees suffer some 

 damage; the Norway maple, white oak, and honey locust, each 

 have one somewhat serious enemy ; the linden, horse chestnut, and 

 soft maple have at least one notorious insect pest; and the elm, 

 cottonwood, and black locust are the most seriously injured of all. 



METHODS OF CONTROL. A great deal can be done to check 

 the spread of shade-tree pests by planting different kinds of trees 

 near each other, rather than massing many of one kind together. 

 Since each insect is usually restricted to one kind of food, the 

 plan ting of different sorts of trees will prevent the spread of insects 

 from one tree to another. This should always be kept in mind 

 when planting a row of trees. For example, the forest tent cat- 

 erpillar is a serious enemy of the sugar maple, but not of the soft 

 maple ; hence if these trees are placed alternately in a row, wan- 

 dering tent caterpillars would have difficulty in getting from one 

 sugar maple to another. It takes many years for a tree to reach 



