748 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 



elevated or margined, and all the ridges marked with black. The pronotum is de- 

 pressed below the surface of the head, but bounded posteriorly by a sharp, elevated 

 backward directed ridge, higher than the mesosternura. All the abdominal segments 

 behind the first (fig. 2a) are furnished with anterior and posterior dorsal transverse 

 rows of minute, sharp, conical tubercles or points, the rows nearly equidistant, those 

 of the movable segments longer than the others, and with the points directed backward. 

 The anterior row is a little more extended than the other, and is formed on most of 

 the seo-ments of larger and more distant points ; in advance of it, at the line to which 

 the posterior edge of the preceding segment reaches, is a shorter, delicate, fine-edged 

 rido-e and a similar but blunter ridge continues the posterior row of tubercles around 

 the body. The very tip of the abdomen (fig. 3a), which is truncated and blunt, bears 

 a slio'ht coronet of points similar to those of the transverse rows. Length, 6"'™; 

 breadth, 1.25"". 



The moth appears to be most nearly allied to the European species B. duplana 

 Hiibn. and R. sylvestrana Curtis. From specimens of the former, which Professor 

 Zeller was kind enough to send me from Germany, it differs by its much smaller size, 

 and the much greater irregularity of its markings, these being almost always clus- 

 tered into four or five narrow, equidistant, transverse belts in R. duplana; a tendency 

 to such a transverse disposition of the markings exists also in B. frustrana, as indi- 

 cated above, but mostly confined to two comparatively broad belts. From B. sijlves- 

 trana, as far as I can judge by descriptions, and by a pair of English specimens sent 

 me for comparison by Professor Fernald, it ditfers by its slightly lesser size, the color 

 of the head and palpi, the differetft disposition of the markings of the wing, and 

 their more brilliant and more highly variegated tints; in R. sylvestrana the stripes 

 are numerous, very slender, and tend toward confluence on the basal half of the 

 win"', giving it a somewhat hoary appearance, in which respect it resembles B. 

 duplana rather than R. frustrana. The pupa of B. frustrana also agrees with that of 

 B. duplana, and is distinguished from that of other Retinice (that of B. sylvestrana is 

 not known) in the rostrate prolongation of the anterior extremity of the body (see 

 figs. 2, 3) ; the close affinity of B. frustrana to the two above-mentioned species will 

 therefore be readily granted. 



Although I have not been able to follow the history of this insect completely, it is 

 probably double-brooded, and diflers therein from the European species, which it 

 most resembles. B. duplana flies in Germany once a year only, appearing by the end 

 of March or the beginning of April, and living some time into May ; the larva is full 

 grown by the end of June or the beginning of July, when it changes to pupa, and in 

 this condition continues eight months in the year. B. sylvestrana is said to appear 

 on the wing in England in Juue and July, and has a similar history to the preced- 

 ing, excepting in its later changes. B. frustrana appears in Nantucket between 

 these two periods, or toward the end of April,* and flies at least during May ; prob- 

 ably most of the brood has emerged by the end of the first week in May. Eggs were 

 seen in one instance May 15. and a nearly grown larva on June 18. Caterpillars may 

 be found fully grown, together with an occasional chrysalid, in the middle of July; 

 a little later chrysalids only can be found ; and again, several years ago, I found 

 larvEe in great abundance, with an occasional chrysalid, about the middle of Septem- 

 ber. Soon after that all change to chrysalids, for, in a subsequent year, Mr. S. Hen- 

 shaw, who visited the island September 17 to 19, and examined the trees carefully, 

 found not more than one-sixth in the larval state, the rest in chrysalis. In all proba- 



* The earliest specimens obtained one year from chrysalids only a week or two in 

 confinement in a warm room appeared on April 25 ; the earliest of those kept the 

 same year in a cellar appeared May 8. A single living moth, and another just dying, 

 were discovered among the twigs confined in a box as late as June 23: how long 

 they had been out of chrysalis there were no means of judging, but possibly several 

 weeks. 



