SHADE TREE PESTS 



47 



Characteristics. The caterpillars of the two species may be readily- 

 distinguished. The forest tent caterpillar has a blue head and a row of 

 10 silvery white spots down the back, as represented in figure 2. The 

 apple tree tent caterpillar has a black head with a bluish white stripe 

 along the back. The former spins its web against the bark of a tree 



Fig. 2 Forest 

 tent caterpillar 

 (after Riley). Fig. 3 Apple tree tent caterpillars and nest (after Riley). 



and on this account its threads are frequently overlooked, while the 

 conspicuous tents (fig. 3) of the latter are familiar objects in many orchards 

 and in wild cherry trees along the roadside. 



Life history. The life histories of these two species are quite similar. 

 The eggs which are deposited in broad belts in June or July around the 

 smaller twigs, those of each species being easily distinguished from the 

 other (see fig 4, 5), do not usually hatch till spring. The caterpillars 

 appear early and feed most voraciously, the forest tent caterpillar com- 

 pleting its growth in June or the first of July, while the other matures a 

 little earlier. The moths emerge the latter half of June or the first half 

 of July and deposit their eggs from which caterpillars come another 

 spring. 



Remedies. The caterpillars of both of these species are very sus- 

 ceptible to arsenical poisons and can be readily controlled by spray- 

 ing, as will be described later. In case the expense attendant upon this 



