87 



sidered, this being especially true of the larva which has been found 

 mining the leaves of several genera of Compositfe, although different 

 species of golden-rod appear to constitute its principal food. The 

 plants upon which the larvte have been observed to make their mines 

 and from which the beetles have been reared include: Soli dago cana- 

 densis^ cees-ia,juncea, et al. ; Bolton ia asteroides,' Sericocarpiis asteroides, 

 or toothed white-topped aster, and several species of the true aster, or 

 starwort. So far as ol^served, this species has confined its attacks to 

 wild plants, but as the Boltonia mentioned and nianv asters are culti- 

 vated it will prol)ably be found to attack some of these in time. 



The beetles eat out little elliptical holes in the leaves of their food 

 plants after the manner of the connnoner M. vittata. Frequently 

 three or four beetles have been observed crowded closely together 

 upon a single leaf of golden-rod. In such cases they sometimes nearly 

 strip the leaf attacked. What is true of the beetle is equally true of 

 the larva^. Unlike the locust-mining species, as many as four larvse 

 can develop in a single large leaf. fJune 24, four pupa? of normal 

 size were found together in a leaf of Solidayo vpesia^ the mine occupy- 

 ing about tlm^e-fourths of the apical end of the leaf. 



It would be a difficult matter to describe the mines accurately, as 

 these are so varial)le and, as previously stated, sometimes occupy a 

 very consideral)le portion of a leaf. The mine, at the point where the 

 pupal cell is formed, puffs up so as to form a hard ])lister, more or less 

 rounded oval in shape, usually a little over an eighth of an inch wide, 

 which sometimes becomes as thick through, its dimensions being- 

 dependent upon the number of individuals which inhabit it. 



The eggs, as might readily be inferred from the smaller size of this 

 beetle, are not so large as those of other species which have been 

 described. They are very closely appressed to the surface of the leaf 

 on which the}" are deposited and are covered with dark, nearly black, 

 excrement, sometimes all the eggs of a group which are placed closel}" 

 together being covered with a conuuon coating. The eggs are usually 

 deposited on the lower side of a leaf, but in one instance a batch of 

 five eggs were found on the upper surface. Most frequently they are 

 placed near the edge, sometimes midway between the tip and the base 

 of a leaf, but generally above the middle. 



The larvae possess the same power as do those of the locust-inhab- 

 iting species of passing from one leaf to another, and larva? in con- 

 finement have been seen in the da\'time crawling out of a leaf and 

 re-entering in a fresh place. Larva? have been noticed to forsake their 

 mines when the leaves were not in a condition that was entirely to 

 their liking. Such desertion of mines was observed on one occasion, 

 June 16, all of the larvae transforming to pupae, and, in due time, to 

 adults, the first imago appearing June 24. 



