108 Journal New York Ent. Soc. [Vol. ii. 



LIFE HISTORY OF FALCARIA BILINEATA/"^?r/vm/. • 



By Harrison C. Dyar, A. M. 



The moths emerge from hibernating pupae and deposit eggs 

 early in June on the white birch {^Bctnla papyrifera). The eggs are 

 laid'from two to four together or singly on the bark of the smaller 

 twigs, usually in a row in line with their longest diameter. On 

 hatching, the little larvae separate, and each proceeds to the tip of 

 a leaf where it takes up a position on the upper side, resting on the 

 brown portion of the leaf which it soon produces by eating away 

 the upper epidermis and parenchyma. Here the first molt takes 

 place. After it, the larva eats the whole leaf, often resting on the 

 same brown patch as it did in the first stage ; but soon it sits upon 

 the green part of the leaf or goes to a new leaf. In its usual position 

 the head and tail are held up at an angle of 45 degrees, the larva 

 being supported on its abdominal feet. In the final stage, when 

 large, the larva usually rests upon a twig or branch. At maturity 

 it forms a slight cocoon of yellow silk between some leaves and is 

 soon transformed to a pupa covered with a white bloom. There are 

 at least three broods annually. The t^g is elliptical, flattened above 

 and below or a little concave. The surface is marked off faintly 

 into irregular quadrangular areas by slightly raised latticed lines 

 and the whole thickly covered with little round regular pits, as 

 many as 10 in each area. Dimensions, .8x.6x 4 mm. The larva 

 throughout its five stages is of a rusty-brown color variegated with 

 white. It becomes paler as it gets older and the mature larva is 

 of a creamy color marked irregularly with white and brown. The 

 surface of the body is somewhat rough at first, the tubercles rather 

 enlarged and later tubercle I becomes distinctly enlarged, forming 

 on joints 3 and 4 a short horn-like process subdorsally. The anal 

 feet are wanting; but there is no long process as in Orcfa rosea ; 

 on the end of the anal plate there is only a short upturned rounded 

 process. In the first stage the arrangement of the tubercles is nor- 

 mal, except that tubercle VI is absent as in the majority of newly 

 hatched larvae. After the first moult several secondary setiferous 

 tubercles appear, the most prominent being one near tubercle III, 

 situated below tubercle III (not in line with it as in Piatyptcryx 

 arcuata) and partly behind the spiracle. The measurements for 

 the width of head for the five stages are : .3 mm., .6 mm., 1.05 mm., 

 1.5 mm., 2.0 mm. If these be compared with the calculated series, 

 viz, .T^T^^ .60, 1. 10, 2.0, ratio .55, it will be seen that an extra stage 

 has been interpolated between the two last stages corresponding to 

 the calculatetl number 1.48, derived with the ratio .74 (=the scpiare 

 root of .55) compare with this the condition in N'adata and Kaema. 

 (Psyche, Oct. 1892, pp. 337—338.) 



