132 FIFTH ANNUAL REPORT 



ISSUING OF THE MOTH. 



The moths commence to issue the fore part of October, the males 

 almost always appearing first. Though the great bulk issue at this 

 season, a few do not appear till the following spring, and occasionally 

 remain in the ground till the second fall — a period of over fifteen 

 months. It is difiicult to conceive what influences should so retard a 

 few individuals, and enable them to pass the heat of a second summer 

 unafiected, when the species normally develops in a so much shorter 

 time ; and, though the exceptional fact is recorded by two independ- 

 ent observers, Mr. Lintner very naturally found it difficult to believe 

 it without additional evidence. I can add my own testimony ; for, 

 from a batch of larvae, which had all entered the ground before July 

 1st, 1871, one moth did not issue till October 8th, 1872. Such abnor- 

 mal occurrences in insect life are by no means uncommon, and, though 

 we may not be able to account for them, we can understand how they 

 prove of advantage to the species. The eggs of our Buck Moth are 

 among the few which remain unprotected and exposed to the severe 

 winter weather, and, indeed, I know of none which are so completely 

 at the mercy of the elements. Now, I have always noticed that some 

 eggs, in a batch, failed to hatch — their vitality having, perhaps, been 

 destroyed during the winter; and Mr. Lintner has recorded a similar 

 observation. An unusually intense cold might destroy all the eggs 

 over large extents of country ; and, in such an event, the few belated 

 pupae would alone survive to perpetuate the species. That species 

 are occasionally reduced in this wholesale manner, we have abund- 

 ant proof; and, in this light, what at first appears to us an abnormity, 

 becomes an important and necessary feature of the insect's economy. 

 Thus, even occasional irregularity plays its part in adapting a species 

 to its surrounding conditions, and becomes a necessary concomitant 

 of the universal order and harmony in Nature ! 



FOOD PLANTS. 



The leaves of our difi'erent oaks are the most natural food of this 

 insect, and the black masses of prickly larvae are sometimes quite 

 abundant on the young Post, Black and Red oaks along the Iron Moun- 

 tain region. My first worms were found abundantly on the Scrub wil- 

 low (S. Immilis), in Northern Illinois, in 1862; and I have also found 

 them on a rose-bush. Maj. J. R. Muhleman, of Woodburn, Ills., also 

 tells me that he has found them abundantly on the common Hazel, 

 and Mr. Glover gives, as food-plant, the wild Black cherry. 



NATURAL, ENEMIES. 



The poisonous qualities of the larval spines, however objectiona- 

 ble they may be to man, do not shield the wearer from the attacks of 



