A REVIEW OF THE AMERICAN MOTHS OF THE GENUS 

 COSMOPTERYX HUBNER. 



By August Busck, 



Of the U. S. Department of Agriculture. 



The little moths belonging to the genus dmaopteryx are probably 

 familiar to an3"one who has collected and observed insects in nature. 

 Who has not occasionally on a warm midsummer day met with a slen- 

 der little streak of gold and silver sitting in the sunshine on a leaf in a 

 protected corner and twirling its long white-tipped antenna in graceful 

 motions? If, when examined more closely, it is found to be a smooth 

 shining little moth, brown with silvery lines on palpi and antenna?, 

 and with a striking broad golden or orange fascia across the outer half 

 of the wing, bordered on both sides by bright metallic scales, then you 

 have a Cosrnopteryx. 



Most of the species may at once be recognized by this characteristic 

 ornamentation alone, without structural examination. 



The genus belongs to the family Elachistidaj, and has the following 

 structural characters: Face and head smooth. Labial palpi verj'^ long, 

 smooth, recurved, pointed; terminal joint longer than second joint. 

 Maxillar}' palpi obsolete. Antennte nearly as long as the fore wings, 

 simple; basal joint ver}^ long. Forewings very long, narrow; apex 

 produced, pointed; 12 veins (or sometimes oxA^ 11, vein 5 being 

 absent); 6, 7, and 8 from a common stalk; 7 to costa; 1 b furcate at 

 base. Hindwing linear with very long cilia; venation limited to a 

 costal and a subcostal vein, and a simple or forked median vein; trans- 

 verse vein, and veins 5, 1, and sometimes 3 being obsolete. Legs long, 

 posterior tibire rough-haired. 



The larvjB are leaf miners, and the mines are easily distinguished 

 from most others by the scrupulous cleanliness with which the larva 

 ejects all its frass through a hole, so that the mine remains clear and 

 white. At maturity the larva changes its color from green to a vivid 

 purple or wine-red, leaves the mine, and spins a matted flattened 

 cocoon of silk. 



Proceedings U. S. National Museum, Vol. XXX— No. 1463. 



707 



