22 THE GYPSY MOTH. 



colonies-* work similar to that of January and February was 

 continued, weather permitting, well into the spring.! More 

 than one thousand acres were thus worked. The under- 

 growth of many colonies in the great pastures of Salem and 

 Swampscott was cut and burned. In former years this win- 

 ter and spring work of egg-killing and cleaning up has been 

 greatly hampered by delay in the legislative grants; this 

 year the granting of the appropriation at a comparatively 

 early date enabled this work to be much more thoroughly 

 done than it has ever been done before, and with correspond- 

 ingly satisfactory results. 



EXPERIMENTS IN KILLING EGGS IN STONE WALLS. 



The moths frequently assemble along stone walls. In past 

 years, when the eggs of the moth abounded in these walls, 

 the walls were torn down, and often had to be rebuilt at a 

 heavy cost. Most of this work has now been done away 

 with. When, in 1897, the young caterpillars hatching in a 

 wall congregated upon the shrubbery, close to either side of 

 it, they were destroyed in quantities, together with the shrub- 

 bery, by the use of the cyclone burner. Trees close to the 

 wall were cut away. If then any living caterpillars were left 

 they were forced to give up the wall as a gathering place (as 

 they then had to go some distance for food) , and were taken 

 later under burlaps on adjacent trees. In cases where full- 

 grown caterpillars resorted to a wall to pupate, they were 

 destroyed by driving the cyclone flame through it. 



Experiments made by Assistant Entomologist Kirkland 

 prove that paraffin gas oil, a nearly crude petroleum oil, is 

 destructive, in temperate or warm w T eather, to gypsy moth 

 eggs. At the suggestion of Supt. C. S. Williams, experi- 

 ments were made in spraying certain stone walls with this 



* Webster defines a colony (under the bead of natural bistory) as a number of 

 animals or plants living together beyond tbeir usual range. In the gypsy moth 

 work the word " colony " has been applied to the moth when it has been found iso- 

 lated from others of its kind by a belt of uninfested territory. 



t The localities referred to here are three great groups of colonies, which have 

 been alluded to in former reports. These groups contain about one thousand acres 

 each. The Saugus colonies centre in the Saugus woods ; the Fells colonies, in the 

 Middlesex Fells ; the Mystic colonies, to the west of the Mystic lakes in the woods 

 of Arlington, Winchester, Lexington and Woburn. 



