INSECT PESTS 213 



Sixth Instar. The stigmatal line is colored like the lighter forms of the fifth 

 instar, but the pink is usually replaced by brown. 



Pupa 



Brown in color, smooth and shining. Abdominal segments punctuated with fine 

 dots which are particularly thick on the anterior half of each segment. Head some- 

 what pointed. At the end of the abdomen are three pairs of hooked spines, one pair is 

 much larger than the others. Length 18-20 mm., width 4-6 mm. The pupa is light 

 green until it is about a day old. 



Adult 



No entirely adequate description of the adult has been found. A de- 

 scription based on reports of Chittenden (28), Watson (148), Douglas 

 (46), and observations of the writer follows: 



The moth averages approximately 37 mm. across the outstretched wings from tip 

 to tip. The body is stout and narrowed at the apex, measuring approximately 12 mm. 

 from head to tip of abdomen. The color varies from grayish tan to dark reddish 

 brown. Under a hand lens the wings have a peppered appearance, black specks show- 

 ing on a lighter surface. A line which may be lighter or darker than the rest of the 

 wing extends diagonally across the outstretched wings from near the anterior distal 

 tip of the forewing to the mid-posterior margin of the hind wing. When the wings 

 are at rest this line may appear as the segment of a circle. The part of the wings 

 distal to the line is darker than the proximal part. The wings are bordered with a 

 brown or yellowish line and are heavily fringed with gray or brown. On the under 

 side of the wings is a row of white dots, consisting of 7 dots on each wing. This color 

 pattern is less variable than that on the upper surface. In the field, a character of 

 value in recognition of the moth is its rapid, spasmodic flight. When disturbed it 

 rises quickly, flies rapidly a short distance, and settles suddenly into the foliage of 

 the host plant. 



Biology. Life-history studies of the velvetbean caterpillar have been 

 made by numerous authorities (148, 46, 73, 122), but many facts con- 

 cerning the biology of this species are still unknown. Apparently the in- 

 sect does not overwinter in the United States except in southern Florida. 

 Watson ( 148) recorded the presence of adults in southern Florida as early 

 as May 1 and found the northward flight of the moth reached southern 

 Georgia and Alabama by September 1. Subsequently, other investigators 

 have observed the northward migration of moths during the sumiTier 

 months and it has been assumed that overwintering occurs only in 

 southern Florida, Cuba and nearby islands. During recent years, the in- 

 creasing damage and early appearance of the insect in southern Alabama 

 and Georgia have led to some speculation as to whether the species is be- 

 coming acclimated to a more northern habitat. Attempts to carry imma- 

 ture and adult stages overwinter at the Wiregrass Sub-experiment Sta- 

 tion in southeastern Alabama have been unsuccessful two successive 

 winters ( 5) . Thus it appears that overwintering does not occur as far north 



