THE COLORS OF INSECTS 201 



Landois, H. Beitrage zur Entwicklungsgeschichte der Schmetterlingsflligel in 

 der Kaupe und Puppe. (Zeitsohr. f. wissensch. Zoologie, xxi, 1871, pp. 305- 

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Weismann, August. Ueber Duftschuppen. (Zool. Anzeiger, i, 1878, pp. 98-99.) 



Dimmock, George. Scales of Culeoptera. (Psyche, iv, pp. 1-11, 23-27, 43-47, 

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Mayer, Alfred G. The development of the wing-scales and their pigment in but- 

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Ueber das Vorhandensein von Schuppenbalg bei den Schmetterlingen. 

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THE COLOKS OF INSECTS 



The colors and bright markings of insects, especially those of 

 butterflies, render them the most brilliant and beautiful creatures 

 in existence, rivalling and even excelling the gay hues of our most 

 splendidly colored birds. The subject has been but recently taken 

 up and is in a somewhat crude condition, but the leading features 

 have been roughly sketched out by the work of a few observers from 

 a physical, chemical, and biological point of view. 



The colors of insects, as of all other animals, are primarily due to 

 the action of light and air ; other factors are, as Hagen observes, 

 heat and cold, moisture and dryness, as recently shown by the ex- 

 periments on butterflies by Dorfmeister, Weismann, W. H. Edwards, 

 and later observers. They have their seat in the integument. 

 Hagen divides colors into optical and natural. 



Optical colors. "These," says Hagen, "are produced by the inter- 

 ference of light, and are by no means rare among insects, but they 

 are solely optical phenomena. Colors by the interference of light 

 are produced in two different ways: either by thin superposed 

 lamellae, or by many very fine lines or small impressions in very 

 close juxtaposition. 



" 1. There must be present at least two superposed lamellae to pro- 

 duce colors by interference. The naked wings of Diptera, of dragon- 

 flies, and of certain Neuroptera often show beautiful interference 

 colors. The wings of Chrysopa and Agrion show interference colors 

 only for a certain time, viz., as long as the membranes of the wings 

 are soft and not firmly glued together. Afterwards such wings be- 

 come simply hyaline. 



