New York Agricultural Experiment Station. 585 



In other States, including Pennsylvania, Massachusetts, New 

 Hampshire, and Michigan a similar invasion is reported. We 

 have sent letters to the entomologists of the various stations to 

 ascertain the extent of the outbreak. 



Action That Is Advised Now. 



Treatment of previously infested fields. — As we shall see later on, 

 the caterpillars are now passing through the pupa stage. They 

 have previously sought shelter under stones, bunches of dried 

 grass, under pieces of board, bits of wood, along the fences under 

 various kinds of rubbish, or have burrowed into the ground to a 

 depth of an inch or two. In each case they have made for them- 

 selves snug cells of earth, or bits of rubbish and earth combined, 

 as the case may be. In these retreats the wonderful transforma- 

 tion from an active caterpillar to an apparently lifeless creature 

 takes place. 



It is evident that, by destroying these pupa?, the moths will not 

 be allowed to develop. This also means the destruction of many 

 eggs. When practicable, therefore, it is desirable to burn over 

 grass land and stubble where the caterpillars have been. When 

 it is not practical to burn the fields over, and where the surface 

 of the ground is moderately even, a heavy roller may be used to 

 advantage. In addition to this, it is well to clear up all rubbish 

 in the infested fields; also along the fences and in the fence cor- 

 ners bordering such fields. From our observations in the field, it 

 seems evident that, when about to pupate^ the caterpillars not 

 only retreat under stones and rubbish, but that many of them find 

 refuge under the matted grass in the fence corners and around 

 the borders of the fields. In districts where infested fields ad- 

 joined the roads and especially where the caterpillars were known 

 to have crossed the road, a careful examination should be made 

 along the fence and under stones, rubbish, etc., along the road- 

 side. If any ])upae are found, the infested section should be 

 burned over if it is practicable to do so. Many of the pupae can 

 be gathered by hand and killed by dipping in kerosene oil or by 

 cushing. Where furrows were plowed to check the insects, and 



