170 



THE LUNA AND POLYPHEMUS MOTHS. 



The two silk-worm moths which we 

 figure this month both possess a point of 

 excellence far in advance of any other of 

 our native silk-worm moths; Luna on ac- 

 count of its graceful form and delicate 

 colors, and Polyphemus for the silk of 

 its cocoons. 



It seems that most persons who speak 

 of the Luna moth (Tropaea luna) feel 

 called upon to give a more or less poetic 

 description of it. This, I hope, has been 

 rendered unnecessary by the colored 

 plate, so that it will suffice simply to men- 

 tion that the beautiful shade of green is 

 of very rare occurrence among our larger 

 moths, and that no other has the long, 

 graceful "tails" on the hind wings, a 

 characteristic which -adds greatly to the 

 beauty of this insect. 



This moth does not seem to be very 

 abundant anywhere, but when once seen 

 will long be remembered on account of 

 its great beauty. The green and yellow 

 colors are evidently very closely related, 

 because either one may, to a greater or 

 less degree, replace the other, so that 

 some of the moths have quite a strong, 

 yellowish tinge. One of our common 

 swallow-tail butterflies (IphicHdes ajax) 

 possesses a very similar green color in its 

 wings, but does not seem to show this 

 tendency to replace the green by yellow. 

 On the wings are four eyespots which are 

 also found in Polyphemus. These are 

 remarkable in that they are transparent 

 in the center. This clear area in Luna is 

 quite small, while in Polyphemus it is 

 about as large as the entire eye spot of 

 Luna. The legs are brown and colored 

 like the front edge of the fore wings. The 

 hairs on the body and at the base of the 

 wing are very long and are white or yel- 



low. The wing expanse ranges from 

 three and three-fourths to five and one- 

 half inches. 



During April or May the mother moth 

 lays her dark-brown or chocolate-colored 

 eggs upon hickory, walnut, beech, oak, 

 and a few others of our forest trees. The 

 limited number of food plants is doubt- 

 less one reason for the rarity of the 

 moths, as compared with such a com- 

 mon and almost omnivorous larva as Ce- 

 cropia. A single moth may lay about 

 one hundred eggs, which are smaller than 

 those of Polyphemus. These hatch in 

 about ten or fifteen days, the larva mak- 

 ing its escape by eating a circular hole in 

 the shell. Occasionally a young larva 

 may be seen crawling about for a short 

 time, carrying upon its head or tail the 

 empty shell. 



The adult larva is about three inches 

 long, of a delicate pale green, a color very 

 difficult to preserve in the dead larva. 

 Those on the plate have lost this delicate 

 green and have become yellow, but show 

 the form perfectly. This larva is very 

 much like that of Polyphemus, but may 

 be distinguished from it by possessing a 

 longitudinal pale yellow lateral line, 

 which is not found in Polyphemus. Since 

 the cocoon is quite thin and contains but 

 little silk, it is considered of but little 

 value. This cocoon is spun among two or 

 three weaves, and is about two inches 

 long. Some authors claim that the cocoon 

 falls to the ground with the autumnal fall- 

 ing of the leaves ; others that it transforms 

 on the ground among the fallen leaves. 

 The cocoon is quite similar to that of 

 Polyphemus, but not so firmly attached 

 when fixed to a stem. The moths emerge 

 in April and May, there being only a 



