FOREST INSECTS 



75 



In Europe the gipsy moth has a number of insect parasites 

 and these serve to reduce its numbers greatly below those 





Fig. 34. Map of the New England states showing the spread of the gipsy moth (Porthelria ditpar). 

 In 1000, twenty years after its introduction near Boston, it had spread over the area marked in 

 black: the cross-hatched lines indicate its distribution in 1905, and the slanting lines its range in 

 1918. 



present in the infested American districts, although as we 

 liave already seen, severe outbreaks in Europe are by no 

 means unknown. In Japan, the species is still less destruc- 



