BIRCH CATERPILLARS. 493 



26. Prionia bilineata (Pack). 



Order Lepidoptera; family Platyptericid^. 



Dr. Diiumock has worked out the history of this iuteresting moth, as 

 will be seen by the following account by Mrs. Dimmock in Psyche, iv, 

 p. 278 : 



Platypteryx bilineata Packard (Proc. Entom. Soc. Phil., Nov., 1864, v. 3, p. 359). 

 Packard (^ c.) writes: "Dr. Harris has reared this from the larva, which pupated 

 July 25; imago August 15." Harris (Entom. Corresp., 1869, p. 142) gives a crude 

 figure of the larva of some Americau species of Flatyjjteryxf, and Packard (Guide 

 Study Ins., 1869, p. 293) repeats this figure as that of a species of Z)ri/o^ito-is; no food- 

 plant is mentioned by either author. The European species, Platypteryx laccrttila, feeds 

 on birch. The larva of P. bilineata is found upon Betula alba, in eastern Massachusetts, 

 about the first of July and again early in September ; hibernation takes place as 

 pupa in the September brood. Dr. G. Dimmock will later describe the egg, larva, 

 and pupa of this insect in detail, but the following notes will suffice for the recogni- 

 tion of the larva and pupa. The full-grown larva is about 12™™ long, tapering 

 from the anterior to the posterior end, which latter terminates in a single point, 

 turned ujiward, in place of the anal legs. The dorsal surface of each segment 

 bears four tubercles, each supporting a single short hair. The arrangements of these 

 tubercles is peculiar : segment 1 has small tubercles arranged thus . . . . ; segments 2 

 and 3 each have large tubercles arranged • . o • (the head in each case supposed to be 

 upward) ; segments 4-10 each have small tubercles arranged •••. ; segments 11 and 12 

 each have two large and two small tubercles arranged • . . • . The slight cocoon is 

 made between leaves of the birch which the larva has drawn together for the pur- 

 pose, and the pupa within it is densely covered with a white bloom. 



Moth. — Female: A delicate thinlj'-scaled species of an ocherous-silvery color ; the 

 ocherous scales appearing along the outer border, and lining the transverse lines. 

 These two lines are in the middle of the wing, the outer being a little flexuous ; both 

 are dark, the inner one lined within and the outer one lined externally with ocherous. 

 A distinct black discal spot. The forewing is thickly covered with long transverse 

 brown strigse or short lines, which become near the outer edge oblique and sinuate, 

 forming an obscure submarginal line. Secondaries paler and dusky perlaceous. Discal 

 dot distinct, and beyond is a transverse dark line, once angulated opposite this spot. 

 Beyond, this line the wing is obscurely strigated. Beneath, the forewings are more 

 yellowish towards the outer edge, and on the secondaries, especially so beyond the 

 outer line, which, with the discal dot, is much plainer than on the upper surface. 

 Head and body thoughout coucolorous with the forewings. Expanse of wings, 1.30 

 inch. 



27. Drepana armata Grote. 



Mr. S. L. Elliot has bred this moth from the birch in Central Park, 

 New York. . It is closely like the European larva, being green, the head 

 broad, the body tapering behind, ending in a sharp point with red 

 spots on the thoracic segments. Mr. Elliot tells me that it rolls up a 

 leaf, and eats a little off", then goes to another leaf, cuts it, and bends it 

 over, and in this way becomes quite destructive.* 



* For a detailed account of the metamorphosis of this moth see my article. The 

 Life-history of Drepana arcuata, etc., in Proc. Brit. Soc. Nat. Hist., xxiv, 1890. 



