THE CANKER WORMS 21 



longitudinal lines, one of which nearly touches the broader lateral line ; ventral 

 surface not quite as dark as dorsal; thoracic legs concolorous with adjacent 

 ventral surface; prolegs somewhat paler on inner side with darker areas on 

 outer surface. Tubercles tipped with a dark spot; setae short and dark: ab- 

 dominal segment 8 somewhat enlarged dorsally. 



Third stage. — Width of head 0.69 to 0.77 millimeter, average 0.73 millimeter ; 

 length when full fed 7.5 to 8 millimeters. General color variable, usually very 

 dark olive-green to dull black with paler markings which vary in color from 

 white to a dirty pale brown. Head brown to dull black with two irregular 

 transverse pale mottled areas across lower portion of head, and additional 

 mottlings of pale dirty brown to white ; longitudinal lines of paler color much 

 as described in previous instar ; ventral surface slightly paler, with a pair 

 of irregular, somewhat broken, paler median longitudinal lines on abdomen 

 to prolegs ; thoracic legs and prolegs about concolorous with adjacent surface ; 

 tubercles inconspicuous, tipped with a darker spot ; setae very minute. Eighth 

 abdominal segment somewhat enlarged dorsally. 



Fourth stage. — (PI. Ill, D). Width of head 1.05 to 1.24 millimeters; average 

 1.12 millimeters ; length when full fed 12 to 14 millimeters. General color very 

 variable, from a reddish brown or olive green to black, with white to yellowish 

 markings. Head dull black with white to yellow irregular mottlings ; just below 

 the middle of the head these markings form an almost solid transverse area; 

 other parts of head irregularly marked, but the upper part mostly black. 

 Dorsal surface with numerous narrow, irregular, broken, paler lines; a broad 

 lateral area following the spiracles pale with numerous longitudinal darker 

 markings; an adjacent area just dorsal to this often the darkest part of 

 body; ventral abdominal surface with a broad longitudinal band of pale 

 yellow to white, broadening out to nearly the width of the body from the sixth 

 to anal segments ; thoracic legs and prolegs concolorous with adjacent body 

 color to somewhat paler. Tubercles small except for two large ones on the 

 enlarged dorsal portion of the eighth abdominal segment; dark at center; 

 setae short, dark. 



Many variations from the types described above occur. Some have a few 

 to numerous dark spots on the dorsum and sides, especially on the second, 

 third, and fourth abdominal segments. 



Fifth stage. — Width of head 1.54 to 1.93 millimeters, average 1.72 millimeters : 

 length when full grown 18 to 22 millimeters. Color and markings extremely 

 variable; general color may be a reddish to a yellowish brown, a yellowish 

 green, a dark blue-black, or any intermediate color. Head dirty white, mottled 

 with brown, the relative proportions of each being variable, the upper half 

 usually containing a greater amount of the darker color, with a dark line 

 along the posterior edge of the head. Body lines irregular, varying in color 

 from pale green or brownish yellow to white ; just below the spiracles a well- 

 defined, narrow, irregular pale line; from spiracles to center of dorsum are 

 numerous lines, irregular, considerably broken, very numerous and distinct 

 in some individuals, to some extent missing In others; usually the area be- 

 tween the two lines next above the spiracles is quite dark. Often the space 

 between the lines just above and below the spiracles is fairly pale, the entire 

 area forming a broad lateral longitudinal band. Ventral surface of abdomen 

 with a broad longitudinal median line of pale yellowish green, which in many 

 cases broadens out from the 6th to anal segment ; central part of ventral surface 

 of thorax green ; thoracic legs paler than body, sometimes tinged with red 

 in places; prolegs concolorous with body to paler; tubercles for the most 

 part inconspicuous ; two on dorsum of eighth abdominal segment raised, black 

 in dark colored individuals and concolorous with body, except at bases of 

 setae, in lighter colored individuals. Setae short, spiracles dark-margined. 

 Behind abdominal spiracles are often swellings, each usually bearing an irregu- 

 lar black spot partially enclosing a smaller irregular spot of white. 



Besides those already mentioned, numerous other irregular fine lines, dot- 

 tings, and mottlings are found in many individuals. 



PUPA. 



Length 7 to 10 millimeters, not as stout as pupa of Alsophila pometaria. 

 General color brown; wingpads greenish brown at first, turning brown later: 

 surface pitted; last segment with a spine, which may be simple, or slightly 

 forked at the end; abdominal spiracles somewhat raised, except those on 

 eighth abdominal segment (PI. Ill, E). 



