212 THE PEANUT— THE UNPREDICTABLE LEGUME 



Description of Stages. Descriptions of the stages and notes on the ap- 

 pearance of velvetbean caterpillar have been published by several writers. 

 The descriptions of immature stages given below are by Watson (148) : 



Egg 



The egg is nearly 2 mm. in diameter and somewhat less in height, and flattened 

 on its lower^ surface. It is prominently ribbed and white until about a day before 

 hatching, when it turns a delicate pink. . . . The eggs are laid singly, mostly on the 

 underside of the leaves, although many are found on the upper surfaces and some on 

 the petioles and stems. 



Larva* 



First Instar. The newly hatched caterpillar is about 2.S mm. long and grows 

 to be from 6 to 7 mm. before molting. The head is light brown in color, rounded, 

 bilobed ; mouth shining ; eyes black. The body is of a uniform light green color with- 

 out any trace of longitudinal stripes. The tubercles are black and conspicuous ; setae 

 also black. The prolegs on abdominal segments 3 and 4 are about equal in size but are 

 much smaller than those on segments 5 and 6 and are not used for walking. A glance 

 at the prolegs is the most ready means of distinguishing the first and second instars. 

 The legs are light brownish yellow. 



Second htstar. The markings are now very similar to those of the next instar but 

 are somewhat less pronounced. The most conspicuous longitudinal mark is the black 

 border to the lateral line. The papillae are black as in the first instar, but there is 

 around the base of each a light-colored ring. The first pair of abdominal prolegs, as 

 in the first instar, is less than a fourth as long as the third, weak, and not used in 

 walking or clinging ; but the second pair is about half as long as the third. These, too, 

 are ordinarily not used in walking but occasionally are so used. 



Third Instar. Head rather square in outline, strongly bilobed, yellowish; ocelli 

 black; mouth dark brown. Body cylindrical; all prolegs used for walking, but the 

 first pair may be somewhat shorter than the others, light yellow; dorsal line pale 

 white, somewhat broken, margined on each side by a darker border. Subdorsal line 

 very pale and indistinct, bordered as dorsal line ; lateral line indistinct and broken, 

 narrow, pale white. Substigmatal line wider and continuous but of a paler color than 

 dorsal and subdorsal. Ventral surface yellowish green. Stigmata brown. Tubercles 

 black. 



Fourth Instar. Dorsal, subdorsal and sub-stigmatal lines more distinct than in 

 the third instar. All feet used in walking, but the first and to a lesser degree the sec- 

 ond pair noticeably shorter than the others. Otherwise this instar is very like the 

 third. 



Fifth Instar. Also similar to the third instar, but the longitudinal lines are more 

 clearly defined. Papillae are now white with brown apexes. In the area between the 

 dorsal and subdorsal lines there are a few white dots with a brown border. One of 

 the largest of these is situated near the anterior border and subdorsal line on abdom- 

 inal segments 1-8. On the metathorax it is double. Stigmatal line is brownish yellow, 

 broken, widely bordered with white on the ventral margin. In the lighter colored 

 individuals this line is often a rich yellowbordered by lines of deep pink. 



3 Surface attached to the leaf. 



* The description given is of the dark phase. As pointed out by Guyton (65) and others, great 

 variation in color occurs after the first instar. The vigorous manner in which the larva wiggles 

 upon being disturbed is an important distinguishing characteristic in the field. 



