and it was thought that the species spread 

 only while in the caterpillar stage, by 

 crawling upon trolley cars, upon automo- 

 biles and other vehicles, and upon the 

 clothes of pedestrians, and that it was 

 thus carried for the most part along the 

 main traveled highways and thus gainerl 

 a large spread. 



Jn consequence, for several years the 

 attention of the government workers w^as 

 focused upon these main traveled roads, 

 and the roadsides were cleaned up to a 

 depth of from 50 to 100 feet, and the 

 trees that w^ere left were banded and 

 sprayed, leaving the roadsides in such 

 condition that there was no possilnlity of 

 caterpillars falling upon passing vehicles 

 or persons. It is undoubtedly true that 

 by this means a far greater spread than 

 has occurred was prevented. 



A MOTir AiCROPLANE 



More recently, however, it has been 

 discovered that a very important means 

 of spread had been overlooked. As the 

 young caterpillar of the gipsy - moth 

 hatches from the egg it spins down on 

 warm days suspended by a silken thread, 

 is caught up by the wind and carried 

 sometimes for miles before it succeeds 

 in attaching itself to a tree or shrub. 

 Large-scale experiments in the last two 

 or three years, conducted by erecting 

 enormous wire screens (see page 41) at 

 various distances to the windward from 

 infested woods, the screens being coated 

 with a sticky substance, have shown that 

 many young caterpillars are carried in 

 this way to a distance of six miles or 

 more. 



This discovery has altered the methods 

 of endeavoring to prevent the further 

 spread of this insect, and as a result the 

 operations are now carried on most in- 

 tensively along the border of spread, es- 

 pecial attention being given to colonies 

 that occur on hillsides, since young cater- 

 pillars from these colonies are more likely 

 to be spread to great distances by the 

 wind. 



Another method of preventing the 

 spread of the gipsy-moth is the inspec- 

 tion of products shipped from the in- 

 fested region. This measure is very im- 

 portant and has been carried on with 

 increasing care year after year. A per- 

 fected system has been inaugurated by 

 the comparatively recently established 



^, 



'^* 



*£t 



Photo from U. S. Department of Agriculture 

 THIS rUBlt CONTAINS I,6oO TINY I'UES, 



Schedins kuvance 



The flies, when liberated, will deposit their 

 eggs in the eggs of the gipsy-moth, thus de- 

 stroying the latter (see page 66). 



47 



