THE COLUMBIA SILK WORM. 891 



stages were published by Prof. C. H. Fernald, in the Canadian Ento- 

 mologist, X, p. 44 : 



Egg. — Subglobose, slightly compressed, the compression being least upon the side 

 from which the yoimg escapes; cream-colored, clouded with reddish brown, and 

 attached to the object upon which the female deposits by means of a dark brown 

 adhesive substance, which appears to be the same as that which is clouded over the 

 surface of the egg, but the greater abundance of it at the jjoint of attachment pro- 

 duces a much darker color. Greatest diameter, 2'"'".; medium, 1|^'"">; least diame- 

 ter, If'"'". The eggs hatched in fourteen and fifteen days after they were deposited. 



Young larva. — Length immediately after escaping from the egg shell, 4'"'". Color 

 black ; some of the individuals show a greenish tinge around the base of the tubercles. 

 Body cylindrical, slightly tapering towards the posterior extremity ; head large,^ 

 rounded, sparsely clothed with long hairs. The second (first after the head), third, 

 fourth, fifth, and sixth segments each with eight tubercles, the lowest one on each side 

 much smaller than the others. The seventh, eighth, ninth, tenth, and eleventh segments 

 have each six tubercles, rather smaller than the corresponding ones on the preceding 

 segments. The twelfth segment has five tubercles, two on each side corresponding 

 with those on the pi'eceding segment in size, and one on the middle of the dorsum 

 of the same size as the upper ones on the third segment. The thirteenth segment ha.s^ 

 four tubercles on the anterior edge, and one at the base of each anal proleg. The 

 tubercles are smooth, cylindrical, gradually enlarging towards the base and at the 

 summit, the least diameter being about two-thirds the way up ; length equal to about 

 three times the least diameter, surmounted with from two (on the smallest) to six 

 finely serrated, radiating bristles, which are about twice the length of the tubercles.^ 

 Duration of this stage, eight to nine days. 



After the first molt. — Length (taken a short time before the second molt), 15""".. 

 Color, pea-green. Tubercles and bristles, mandibles, palpi and anteume, a spot about 

 the eyes, a stripe on each side of the clypeus, the legs and a spot on the outside of 

 the prolegs black, second, third, and fourth segments each with four black spots on 

 the posterior edge, and a row of black spots on each segment after the head, on th& 

 line of and behind the stigmatse. Duration of this stage, five to seven days. 



Jfter the second molt. -Length (taken soon after the second molt), 20'"'". Color,, 

 pea-green, with a bluish tint upon the dorsum. Black markings as in preceding 

 stage. Duration of this stage, four to five days. 



Jfter the third molt. — Length, 35'""'. Color, pea-green, lighter on the dorsum. 

 Marked with black as in the two preceding stages. All the tubercles with the basal 

 portions blue, except those on the second segment, and the lower one on each side of 

 the third to the sixth segment inclusive. Duration of this stage, six to nine days. 



Jfter the fourth molt. — Length, 50'"'". The head at the time the larva escaped 

 from the egg-shell was proportionally large, but during the succeeding stages it did 

 not grow so fast as the other parts of the larva, and at the beginning of this stage,, 

 but more especially at its close, it was proportionally small. Duration of this stage, 

 ten to twelve days. 



Mature larva. — Length, 76'""' (about 3 inches). Thickness between the segments, 

 13mm. of largest part of segment, 15""". Head pea-green, sparsely clothed with fine 

 yellowish hairs. Mandibles and outer joints of antenna}, and palpi, spot about the 

 eyes, two spots on the gular (these may have occurred in the previous stages, but were 

 not observed), and a stripe on each side of the clypeus, black, the latter sometimes 

 wanting. Basal joints of autennje and palpi and the labrum greenish blue. General 

 color of the body pea-green, rather lighter than the head, and lighter above than on 

 the sides, with the faintest tinge of blue between the segments. Last joint of the 

 legs and claw black. Stigmata oval, white, surrounded by a fine black line. 



The tubercles were greatly changed at the fourth molt, both in form and color. 

 The first and lowest on the second segment is small, conical, black, and surmounted 



