ALDER CATERPILLARS. 625 



I have mentioned this insect above as an undetermined Cossus ; that it is one of 

 the Cossidae there can be, I think, no doubt, and as I understand the descriptions of 

 the preparatory stages of the genus Cossus, it seems to me that it belongs to that 

 genus ; therefore I will, for brevity of reference, call it provisionally Cossus alni. 

 It certainly is clearly distinct from C. centerensis, whose larva and pupa I have had 

 an opportunity to examine from poplars at Corunna, Mich.; in fact, it appears to be 

 distinct from any species whose history is known. It may prove to be one of the 

 doubtful or partially known species. I am aware that Mr. Lintner has referred to a 

 Cossus which bores in the trunk of white birch ; I am also mindful that insects are 

 as a rule pretty good botanists, and that Betula and Alnus are closely related plants, 

 so this insect may prove to be the one discovered in the birch by Mr. Lintner. It 

 ought not to be a difficult matter to obtain the moth in May or June next. 



INJURING THE LEAVES. 

 4. Papilio rutulus Boisduval. 



An inhabitant of the Pacific coast, this caterpillar has been found by 

 Mr. Henry Edwards to feed upon the alder {Alnus viridis). Three cater- 

 pillars were obtained from eggs observed to be deposited by the female 

 July 8 ; the caterpillars hatched July 13, the first molt occurred July 

 15, the second July 18, and the third July 22 ; the fully grown cater- 

 pillars have not yet been observed. (Papilio, ii, 112.) Mr. W. H. 

 Edwards afterwards reported that the eggs are laid on the willow in 

 northern California (Papilio, iii, 65). The following description of the 

 early larval stages is by H. Edwards. 



Larva on exclusion from eyg. — Head very large, black, shining. Second segment 

 with two tubercles on the sides in front. Body brownish black. Segments 3, 4, 5, 

 10, 11, 12 with two tubercles each, arranged subdorsally. Extending from the sev- 

 enth to the ninth segment is a small, but conspicuous, triangular white patch, the 

 vertex of which is directed posteriorly. Feet and legs black. 



After first molt. — The head now becomes pitchy, the body streaked with shades of 

 brown, longitudinally ; the two tubercles on second segment are chestnut-brown, and 

 the whole of the processes brighter and more glossy. The white triangular patch is 

 larger and more distinct, and the posterior segments are delicately mottled with 

 brownish. 



After second molt. — Head chestnut-brown, with pinkish tinge. The tubercles of 

 the second segment are larger than before, and have become yellowish-brown in color. 

 Between them is a yellowish corrugated fold, and on the dorsum, at the base of the 

 longer tubercles, are two smaller ones, also chestnut brown. Body brownish dor- 

 sally, with a green tint throughout; laterally it is pale apple-green. The third seg- 

 ment has six tubercles, the middle and lateral being exceedingly small. Fourth seg- 

 ment swollen, the body here attaining its greatest size, This segment has also six 

 tubercles, the two dorsal being the smallest. The fifth segment has four tubercles, 

 the smaller pair of which are placed anterior to the other. The triangular patch 

 has now become cream-yellow, and encroaches in a point posteriorly on the ninth 

 segment. Segments 9, 10, 11, 12, 13 have each two tubercles, which are directed 

 backward, and increase posteriorly in size, so that those of the thirteenth segment 

 are double the length of those of the ninth. Mouth parts, legs, as well as the whole 

 of the under side, pale bluish green. 



After third molt. — The head is now pale bright chestnut, with a decidedly pinkish 



lint, and the mouth parts of a deeper and more decided green. The body has 



assumed a pale apple-green color, the tubercles are brighter and more approaching 



to brownish orange, and the triangular patch is buff, with some streaks of green run- 



5 ENT 40 



