TWENTY-FOURTH REPORT OF THE STATE MUSEUM. 



VI. TRANSFORMATIONS OF DAREMMA UNDULOSA WALKER. 



A moth of this species, with broken and denuded wings and con- 

 tracted abdomen, which was taken on the 8th of July, deposited 

 eight eggs the following day in the box in which it was confined, 

 and died three or four days thereafter. Upon examining the box on 

 the 14th, there were found the transparent shells of six of the eggs 

 from which the larvse had emerged, the other two proving infertile. 

 Three of the larvae had escaped, and the remaining three were quite 

 feeble from their compulsory fast of probably a day or two. but very 

 soon commenced feeding on some tender leaves of ash (Fraxinus) 

 which were given them. To insure them a continual supply of 

 fresh food, they were placed on a leaf of a growing ash and inclosed 

 in a gauze net for their protection.* 



Young larva. The larva is of a very pale green color throughout, 

 showing no stripes nor bands. Its length is 18-100ths of an inch. 

 Its caudal horn is cylindrical, straight, of a light green color, except 

 its tip, which is brown, and measures 8-100ths of an inch. 



*The rearing of larvae upon growing plauts, as above referred to, is becoming a favorite method 

 with lepidopterists, for several reasons?: It affords a constant supply of suitable food, free from the 

 partial decomposition which commences almost immediately upon the plucking of the leaf, or from 

 the rapid change, commonly known as " souring," which a twig or stem undergoes when placed in 

 water. The great sensitiveness of young larvae to improper food, is well known to those who have 

 reared from the eggs, by the usual method of plucked food, broods of our sphinges, in which a mor- 

 tality of one-half has often been encountered before the first molting. The larvae require but little 

 attention; during their infancy, the few leaves upon which they are at first placed, may suffice for a 

 week or two ; as they attain a size which demands a larger supply of food, as often as the inclosed 

 leaves are consumed, it is only necessary to open the net, turn out the excrementitious matter, clip 

 off the defoliated portion of the twig, and tie again farther down the stem. It prevents the injuries 

 'which so frequently prove fatal to young larvae, when the slightest degree of force is employed in 

 removing them to fresh leaves. In addition to natural food, it also gives a natural exposure, an 

 important consequent of which is, that a description of the larva need not be imperfect from abnor- 

 mal coloration, which so frequently is the result of in-door rearing. 



There are, however, some risks to be incurred by this method. The larva sometimes deserts the 

 leaf for its enveloping net, when of so small a size, as not to be able to protect itself against being 

 seized and destroyed by ants or other insects ; and this traveling propensity is often the first indica- 

 tion of approaching molting, which is always accompanied by diminished powers of defense. As I 

 know of no means by which to prevent such occurrences, which are very annoying when the larva 

 happens to be rare, I would, in such cases, defer placing them out of doors until their second change 

 had given them a degree of safety in the size attained. As they approach maturity, the protection of 

 the net does not wholly exempt them from the attack of their natural enemies, the Ichneumonidse, 

 which, readily drawn thither when several larvae are associated, may often be seen prospecting over 

 the net for a position whence they may reach with their ovipositor the body of their prey within. 

 Having thus lost a number of rare larvae, I am now usually successful in preventing its recurrence, by 

 instructing the net of a large size, and extending it with two or more wire rings, so as to place the 

 inclosed larvae while upon the leaves, which they rarely leave after their second molting, out of ovi- 

 positor reach. 



When nearly ready for their pupal change, they should be removed from the tree, and fed to matu- 

 rity in a box or wired breeding cage, to guard against their liability to escape at this period, by 

 forcing an opening in the netting. 



