SPECIAL PROBLEMS OF INSECT CONTROL 161 



great distances from the original colony. Windstorms also 

 aid in furthering the flight, and steam cars and trolleys trans- 

 port these pests. Besides the injury to orchard, shade tree, 

 and forest, the brown-tail caterpillar inflicts serious pain upon 

 many persons. This is caused by fine hairs which pierce the 

 skin, the irritation becoming severe enough in some cases to 

 cause illness. A free use of 

 vaseline will give relief. 



The brown tail cannot be 

 controlled by an attack upon 

 the eggs, since they are usually 

 on the leaves and for a short 

 time only. Spraying is em- 

 ployed to destroy the swarm- 

 ing caterpillars, but the most 

 effective method is destruc- 

 tion of- the winter nests. These 

 are conspicuous on the tips of 

 branches between August and 

 April. They may then be cut 

 with pole shears, and must be 

 carefully collected and burned. 



Parasites. The great aim 

 in the attempt at control of 

 any pest is to discover its nat- 

 ural enemy. In the case of 



insects like the gypsy and brown-tail moths, a series of para- 

 sites is necessary, for the parasitic insects restrict themselves 

 to one stage only in the development of their host. The insect 

 which attacks the egg takes no notice of the caterpillar, and 

 the insect which attacks the caterpillar is never found upon 

 pupse. Several native parasitic insects are known to attack 

 these pests, and many have been imported ; but as yet the 

 series is not complete and has failed of effective control. 



FIG. 79. Brown-Tail Moths 



Four egg masses and two moths laying, 



July 10. Photograph by Katharine E. 



Dolbear 



