20 



onally by black lines and shades. The lines have a tendency to become 

 toothed or scalloped, and the wing margins themselves are also a little 

 notched. The worms first appear on the bogs in June and become 

 full grown by the end of that month or early in July. They are then 

 rather more than an inch long; slender, smooth, livid gray caterpillars 

 with a deeply indented head and a long, pointed anal plate. They 

 have three pairs of short legs close behind the head and two pairs 

 near the anal end. When they walk, they first stretch out at full 

 length, take hold with the anterior legs, then bring the posterior pairs 

 close to the others, the middle of the body forming a loop. This 

 mode of progression gives them the common name " loopers" in addi- 

 tion to those already mentioned. At rest or when not feeding, the 

 caterpillars hold fast by the anal legs only, and stretch out the remain- 

 der of the body at an angle, and so rigidly that they resemble leafless 

 bits of vines. On a section of bog on which they have been feeding 

 the observer may stand in the midst of thousands of them and see 

 none until something starts them into motion; then it appears almost 

 as though the entire bog was alive. 



When full grown they bury themselves a short distance beneath the 

 surface and change into rough, brown, rather stubby pupse, from 

 which the moths emerge a few days later. The second brood of cater- 

 pillars matures early in August, and pupation begins before August 9. 

 Though worms will continue to be present in numbers until after 

 the middle of the month, the moths appear at its end and in September. 



There seems to be no regularity in the appearance of these insects. 

 In some 3'ears they are not seen at all; in others thej^ may be locally 

 abundant, and onl}^ occasionally do they seem to occur everj^where in 

 great armies. Usually they start from some point near the edge of the 

 bog, spread out a little, and then move in an almost direct line ahead. 

 Sometimes the beginning is nearer the center, and the eating may be 

 in all directions from a given point where some groups of eggs were 

 laid. It is the first brood which, as a rule, starts near the edges. 

 The second brood starts from inside centers, and when these are numer- 

 ous the boundaries of the individual broods become lost, and, the 

 masses uniting, an army is formed which, as it advances, plays havoc 

 with the crop. Not a green thing is left on the vines, and in a few 

 days acres may change from green to brown; from a smiling promise 

 of a full crop to the barrenness of desolation. 



Remedial measures. — Being an open feeder upon the foliage, this 

 span worm is susceptible to arsenical poisoning, and unless the bogs 

 can be rapidl}^ reflowed and as rapidly laid dry, spraying or dusting 

 are the only alternatives. Where the worms are noticed when they 

 first start, spraying the foliage just ahead of them may answer all pur- 

 poses, and indeed this poisoning of their line of advance should always 

 be done before treating the parts already infested. Either Paris green, 



178 



