REPORTS OF OBSERVATIONS AND EXPERIMENTS. 23 



more inches in width. For this purpose may be mentioned tar. printer's 

 ink. molasses, melted India rubber, and a mixture of oil and resin 

 boiled together. These bands should be placed upon the trees a short 



time before the first moth issues from the ground, and should remain 

 upon the trees until the last moth of the season is dead. My notes 

 indicate that in southern California this period extends from about 

 January 1 to the latter part of April, and daring this period the sticky 

 substance should' be renewed at short intervals, never allowing it to 

 become sufficiently hard to permit of the moths passing over it. After 

 the last moth of the season has passed away the bands should be 

 removed from the trees, and thoroughly scalded, in order to destroy any 

 eggs that may have been deposited upon them. 



For a description of the numerous devices that have been employed 

 for the purpose of preventing the female canker-worms from ascending 

 the trees and depositing their egg>. the reader is referred to the Third 

 Report of the United States Entomological Commission pp. 1 



ProcKcerodes nubilata Pack. — This is a second kind of span-worm 

 that sometimes occurs in destructive numbers on the cultivated Eng- 

 lish walnut in southern California. It does not confine its attack 

 this tree, however, as I have frequently found it upon apple and 

 willow: but it appears to prefer the English walnut to any other tree. 

 This span-worm is considerably flattened, and during the day time 

 remains at rest in a crevice or other irregularity in the bark of the 

 tree, and being of nearly the same color as the bark its presence is not 

 easy to detect. In this respect it closely resembles the caterpillars of 

 the red underwinged moths [Catocala), but is readily distinguishable 

 by possessing only two. instead of eight, abdominal prole.-. 



This span-worm has the same general appearance of the walnut 

 span-worm referred to above, except that the tubercles or piliferous 

 spots on various parts of the body aie of nearly a uniform size, win 

 in the latter some of those on segments I. 5. 6, and 11 are much lai - 

 than the othe 



When jarred from their perch these span-worms, in common with 

 other members of this group, spin a silken thread, by mean- of which 

 they remain suspended in the air. I have never observed them assume 

 a rigid attitude, attached to some object by the tour posterior pn 

 alone, a habit so common in related forms. Instead they rest with the 

 body closely appressed to the bark of the I 



The eggs from which these span-worms batch are deposited singly, 

 being attached at one of their sides. The young span-worm, in issuing 

 from the egg. makes its escape through a circular opening in the flat- 

 tened end. The full-grown span-worm secretes itself inert •. s i the 

 tree, usually beneath a loose piece of projecting bark; here it spins a 

 thin cocoon, and shortly afterwards assumes the chrysalis form. 



Iffy imtes indicate that at least three broods «>f these insects arc pro- 

 duced in one year; the winter is passed in the larva state, and the 



