ISO FIRST ANNUAL REPORT OF 



THE THISTLE PLUME,— Pterophorus carduidaclijlus, N. Sp., PL 2, 

 Figs. 13 and 14. 



(Lepidoptera Alucitidse.) 



Having already sketched the history of the Grape Plume, page 

 137, the larva of which attacks the Grape vine, I will now give the 

 history of another species of the same genus whose larva infests the 

 common Thistle (Cersium lanceolata) in order to show how very dis- 

 similar two larvre may be, which belong to the same genus and greatly 

 resemble each other in the perfect state. 



During the month of May the heads of the above named thistle 

 may frequently be found drawn together by silken threads, with some 

 of the leaves frequently dead. On pulling this webbed mass apart 

 from eight to a dozen thick smooth worms may be found, which are 

 of a light straw color with rows of black spots, and the head and tail 

 [Fig. 98.] marked as in the accompanying figure. These worms are 

 found of different sizes in the same head, which would in- 

 dicate that the parent moth either deposits her eggs at dif- 

 ferent intervals in the same place or that the eggs hatch 

 out irregularly. Towards the end of May they change to 

 pupae within the burrow which the worm inhabited; these 

 pupro being of a dull yellow color, without polish, and re- 

 sembling the pupae of some long-legged Crane fly (Tijpula) 

 rather than a moth — see PL 2, Fig. 14. In just one week 

 after they have thus changed, the moths escape. This moth, which is 

 represented at Plate 2, Figure 13; is of a tawny yellow color, with a 

 prominent triangular dark spot on the outer third of the front wing, 

 running from the front edge. As it differs from all hitherto de- 

 scribed North American species, it may appropriately be called the 

 Thistle Plume. 



Pterophoros cardctidactylus, N. Sp. — Larva. — Average length 0.60. Largest in the middle of 

 body, tapering thence each way. Color light straw-yellow — greener when young. Somewhat darker, 

 partly translucent, dorsal, subdorsal and stigmatal lines. Two lateral rows of black spots, the 

 lower spots rather smaller and placed behind the upper ones. A third row above these, and others 

 along the back, hut so small that they are generally imperceptible with the naked eye, except on the 

 thoracic segments, being especially distinct on segment 2. Head small, black, sometimes inclining 

 t . brown. Cervical shield black, divided longitudinally in the middle by a lighter line. Caudal 

 plate also black. Segment 11, besides the spots above mentioned, has two transverse black marks, 

 the posterior one the largest. Thoracic legs black, the others of the same color as the body. 



Described from 12 specimens. 



Pupa.— Average length 0.15. Of form of Plate 2, Figure 14. Soft, dull yellow, with a lat- 

 eral dusky line, each side of dorsum, and another, less distinct each side of venter. Also 

 dusky about the head and wing-sheaths. 



Perfect insect. — Length 0. 15; alar expanse 0.S0. Front wings bifid, the cleft reaching not 

 much more than J of wing : tawny yellow, with a distinct dark brown triangular spot running from 

 Costa to the base of cleft — sometimes a little below it — its posterior margin with a slight concave 



curve. Three dusky, difl'use longitudinal spot , (dared on the basal third of the wing at costa 



and frequently reaching along the costa to the triangular spot ; one near the interior margin, a lit- 

 tle nearer to the base of « ing I nan the Last, and one on the outer third of the interior margin. Two 

 light-colored transverse linos across the end of wing, one very near and parallel with posterior 

 margin, the other bordering the triangular spot behind, and curving across the lower lobe towards 

 posterior angle. The space between these two light lines usually darker than the ground-color. 

 Fringes dark with a light margin. Hind wings trifid, the upper cleft reaching a little beyond the 



