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Show APPENDIX C.- INSECTS. 879 LETTER FROM T. R. PEALU, ESQ., UPON THE LARVAE OF INSECTS FOUND IN THE GREAT SALT LAKE. WASHINQTOW, May 12th, 1852. MY DEAR SIR:- The exuviae of insects which you have brought' from the shores of the Great Salt Lake proves, on examination, to nave been deposited by aquatic diptera. In the mass, I can detect fragments of the larvae shells of the pu^ a, and small* portions of a mature Chironomtis and other Tipulidae. More than nine- tenths of the mass is composed of larvae and exuviae of Chirohomu*, or some species of mosquito- probably undescfibed; the fragments being too imperfect to determine. You are best able to determine, first, " whether mosquitoes exist at any time at the Great Salt Lake in such unparalleled numbers as this organic matter indicates; or, secondly, whether the salt of the lake water has preserved their exuviae, so that it has accumulated through a great length of time. A few fragments of insects I have been able to determine as belonging to the Linnaean genus Nepa, which is aquatic, and a very few others as' Hymenopterous, & c. In the hope of soon seeing your Report on the most interesting portion of our continent, I remain Yours truly, T. R. 3* EALE. CAPTAIN H. STANSBURT, Corps Topographical Engineers, Washington. I am not aware that mosquitoes exist in such unusual abundance in the vicinity of the lake; but incline to the opinion , of Mr. Peale, that the accumulation of the immense masses of these exuviae is to be attributed to the preservative qualities of the lake water. H. S. |
