CCXIX 

 "age of MISSOURI PORPHYRIES."* 



Having just fexamined a suite of the Huronian rocks of New Brunswick, 

 also those of Massachusetts, I find them to be made up of a variety of Por- 

 phyries, identical in appearance, and apparently in composition, with 

 those of Southeast Missouri; in fact, their resemblance is such that if I* 

 had been shown such specimens without a knowledge of their locality, I 

 should at once have pronounced them to be from Missouri. 



I would remark that these Eastern rocks are of various shades of color, 

 from light red, or pink, to black and gray, both coarsely porphyritic and 

 cryptocrystalline, and have also similar intrusive dykes of Dolerite, Dior- 

 ite, and Porphyrite, like those of Missouri. We may, therefore, call our 

 Missouri porphyries Huronian. 



ENTOMOLOGICAL NOTES. 



Ne~ju Wheat Destroyer. — Mr. Riley exhibited specimens of a worm that 

 was just at this time devastating the wheat fields of parts of Kansas, and 

 particularly of Dickinson County. It does not eat the blades, but attacks 

 the heads. Specimens had been sent to him last week by Mr. John W." 

 Robson, of Cheever, but in transit they had. all eaten out and escaped from 

 the paper-box in which they were enclosed. On the way, however, they 

 had molted, and from the heads alone Prof. Riley had determined the spe- 

 cies to be Leucania albilinea, though the insect had never before been 

 reported from the West as injurious. Ot]ier specimens just received from 

 Prof. F. H. Snow, of the State University at Lawrence, and from Mr. Jno . 

 Davis, editor of the Tribune at Junction City, proved the correctness of 

 the determination. The species is generically allied to the common 

 Army-worm, and may be popularly called the Wheat-head Army-worm. 

 As it had never till lately attracted unusual attention, too little was yet 

 known of its habits to warrant any suggestion as to the best mode of de- 

 stroying it. 



Mite Parasites of the Colorado Potato-beetle. — Mr. Riley also exhib- 

 ited a specimen of Doryphora lo-lineata that was so completely covered 

 with a mite parasite belonging to the Gamasidee and allied to the Euro- 

 pean Uroploda vegetans, that the point of a needle could not be placed on 

 any part of the beetle's body without touching one of the parasites. He 

 estimated that there were over 800 of the mites, and they had killed their 

 victim. Aside from the toad and other reptiles — the crow, rose-breasted 

 grosbeck, and domestic fowls, among birds — which prey on this potato 

 pest, he had, in his Reports, figured or described no less than twenty- 

 three insect enemies that attack and kill it. Only one of these is a true 

 parasite, and the mite exhibited made the second or just two dozen insect 

 enemies in all. 



He mentioned the fact, in this connection, that the Doryphora had 

 reached into New Hampshire, and was doing great injury along the At- 

 lantic coast. 



* Trans. St. Louis Acad. Sci., vol. iii. No. 3, p. 366. 



