JOURNAL 



jOFfD "Qnvk €in(oniQlogirfll[ ^oriFJ^g. 



Vol. XXX. December, 1922. Xo. 4 



STRATIOMYIID LARV^ AND PUPARIA OF THE 

 NORTH EASTERN STATES. 



By O. a. Johannsen, 

 Ithaca, N. Y. 



For some years, I have collected, as occasion offered, the imma- 

 ture stages of Diptera and in this way have accumulated a number 

 of the larv?e and puparia of the Stratiomyiidae, among which there 

 are three genera, fourteen species in the last instar, and seven species 

 in earlier instars which have not heretofore l)een described. As it 

 may be of interest to entomologists I am offering here a key to the 

 known early stages of genera and species occurring in the North 

 Eastern States. In view of the number of additional forms included. 

 I believe no apology is needed for publishing a paper on this sub- 

 ject so soon after the appearance of the excellent table included by 

 Mr. INIalloch in his work, published in 1917. 



That there is secreted by the hypodermis of the larvae of this family 

 a heavy deposit of calcium carbonate has long been known. This 

 deposit, which forms on all parts of the body, including the append- 

 ages of the head, is sometimes so thick and dense that it obscures 

 the outlines of the more delicate parts and renders their study diffi- 

 cult and sometimes impossible. By dropping the insect in dilute 

 hydrochloric acid for a moment, until the active effervescence ceases, 

 the deposit is removed and the integument rendered beautifully clean. 

 Placed in a 10 per cent, solution of caustic potash for 24 hours or 

 until the darker mouth parts become pale, it can then be freed from 

 the dissolved internal tissues, dehydrated, cleared and mounted in 



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