Gi ENTOMOLOGICAL SOCIETY OF ONTARIO. 



membrane of the underside, loops or gatherings, corresponding in some measure to those 

 of the upper side, but could see none or anything resembling them. The membrane 

 appeared only roughened and wrinkled. It was extremely thin and very frail, and the 

 base of the loops seemed to be attached to its inner surface. The thought occurred to me 

 that this would account for my inability to draw out the membrane of the winglet, and 

 will in a measure explain the reason for the comparative slowness of their expansion as 

 compared with butterflies. That is, supposing the wings of butterflies are constructed 

 upon a different principle ; but this is a point which will require much more careful 

 investigation than I have given to it. 



The extent to which the fluid of the insect gives color to the scales is a very inter- 

 esting subject for consideration. The fluid difiers in color in difl'erent species. The color 

 of the fluid decides the color of the membrane in the expanded wing ; but to what extent 

 it affects the color of the scales is not so easily determined. 



Prof. V. L. Kellogg, in his able and interesting paper, "The Taxonomic Value 

 -of the Scales of the Lepidoptera," which appeared in the Kansas University Quarterly, 

 for July, 1894, on page 49 says: "The scales are attached to the wings by means of 

 their short pedicels fitting into minute pouches or cups on the surface of the wing mem- 

 brane. . . . The cups sink but slightly into the wing-membrane, the outer open end 

 being at the surface of the membrane, and the inner closed end or bottom of the pocket, 

 being only slightly below the surface. . . . Thus the cups are more truly little 

 pockets on the surface of the wing, than pits or cavities in it." On page 50 he says : 

 '' The pedicels of the scales are of slightly varying shapes and of different lengths, corres- 

 ponding with the pockets into which they fit. Those which enter insertion-cups which 

 are expanded at the base, or at some point between the base and the mouth, present at 

 the tip or between the tip and the point of merging into the blade of the scale, respect- 

 ively, a slight expansion, so that they are pretty firmly held in the cup by a sort of ball 

 and socket attachment." 



These quotations convey no intimation that there is any opening at the top of the 

 scale, or that the tip passes through the inner surface of the membrane, whereby the fluid 

 could enter the scales whilst flowing between the upper and under membranes of the 

 wings. And yet I think we have positive proof that in some instances the fluid does 

 enter the scales and influences to some extent their color. 



When commencing his description of the structure of scales, the Professor, on page 

 51, says : "The scales are flattened sacs, composed of two membranes, enclosing some- 

 times only air, sometimes pigment granules attached to the inner face of one of the mem- 

 branes, and sometimes (as observed in cabinet specimens) the dry remains of what may 

 have been during life an internal pulp." Here in a foot note, Prof. Kellogg refers to 

 Minot and Burgess, who, in their description of the anatomy o{ Aletia, declare that in all 

 of the scales examined by them there was always an internal pulp which contained color- 

 ing matter. Then on page 09 Prof. Kellogg states that : "The colors of scales are pro- 

 duced by two causes: (1) The presence of pigment; (2) The overlapping, lamination 

 and striation of the scales which produce those familiar but striking optical phenomena 

 due to the interference of the waves of light. Combinations of these causes are usually 

 present, so that the resulting color eflfects are practically incapable of analysis." 



But there is a third cause of coloring. The long, slender scales on the winglets of a 

 newly emerged luna are as pure a white as those upon the abdomen ; when the wings are 

 expanded these same scales are tinged with yellow. Whence did they obtain it 1 It is a 

 well-known fact in the coloring of materials that a small quantity of green entering a pure 

 white, a yellow is the natural result. Therefore the conclusion to me is irresistible, that 

 a portion of the green fluid passing between the membranes of the expanding wings 

 entered the scales — not enough to make them green, but sufiicient to make them yellow. 

 And there may be other lepidopterus insects which have the color of their scales modified 

 in a similar way, but which will have to be detected by observing and comparing them 

 in their unexpanded state with those on the expanded wing. The scales on an undeveloped 

 wing are as much compressed, in proportion to their size, as the wing itself. As it 



