PLUSIA DVAUS : TRANSFORMATIONS. 



95 



and whitish-green over the back. The dorsal vessel is apple-green 

 with its borders well-defined by white lines, contracted at the incisures 

 and considerably enlarged centrally upon each segment. Below the 

 dorsal vessel is a whitish shading, inclosing the anterior of the trape- 

 zoidal spots, and extending nearly to a pale whitish-green subdorsal line 

 which is angulated on each segment beneath the posterior trapezoidal 

 spot; there are also two lateral similar colored lines above the spiracles, 

 the lower of which runs nearly straight, while the upper one is quite 

 toothed or crinkled. The spiracles are of a pale orange color. Each 

 ot the usual piliferous spots bears a pale-colored hair of the average 

 length of one-fourth the diameter of the body. In addition to these, 

 there are a number of corneous yellowish dots scattered, or grouped in 

 short rows, upon the sides. The body slopes abrujjtly from the crown 

 of the eleventh (penultimate) segment to the anal pair of prolegs. The 

 legs are long, watery-green, and transparent ; the prolegs are dull green 

 with their plantae tinged with red. 



In one of the examples, the slightly elevated piliferous spot above 

 the spiracle on each segment, is black, as are also all of the like spots on 

 the head, of which there are four conspicuous ones arranged in a rhom- 

 boid. All of the setiferous spots of the first segment are also black, as 

 are the two dorsal ones on segments two and three ; those on segment 

 eleven are annulated with black. 



The caterpillar is a rapid and seemingly a greedy eater, and is not 

 easily disturbed when feeding. Its large excremental pellets are dis- 

 tributed over the leaves to which they adhere. At times it assumes the 

 favorite position of many of the Geometricke when at rest. Sustaining 

 itself with its prolegs, it elongates the detached portion of its body and 

 extends it at a considerable angle with the leaf or stem — the three pairs 

 of true legs scarcely visible from being folded upon one another and 

 ui)on the body and directed forward in range with the head similarly 

 projected. 



Transformations. 



The larvK were brought to me on February loth, when they were 

 nearly full grown. They were fed upon the leaves of the Wandering 

 Jew. Two of the number spun up in slight cocoons made of fine 

 threads within the leaves on the 13th. The cocoons were of so slight a 

 texture as hardly to deserve the name when compared with some of the 

 architectural marvels which many species of caterpillars construct for 

 shelter and protection during their long months of pupation — firm as 

 parchment, double-walled to exclude wet and to regulate temperature, 

 with an accurately adjusted lid in some cases for the escape of the inclosed 

 insect, and with other wonderful contrivances for, and adaptations to, spe- 



