SEPTEMBER. 423 



testimony, founded on his own experience. The same meth- 

 od has been long practised in New England, and with good 

 success, for the destruction of canker-worms. In some cases 

 it may not be possible to discover and destroy all the worms 

 that have come to the ground, especially beneath large trees 

 growing among grass ; and the insects will attempt to regain 

 the leaves by creeping up the trunks. By surrounding the 

 latter at the bottom with a thick coat of tar, the upward 

 progress of the worms will be effectually prevented. In this 

 way tens of thousands of canker-worms have been caught in 

 the College grounds in Cambridge, during the past spring, 

 and have perished in the tar. Early in the spring, Avhile the 

 worms are young and tender, they may be killed by syringing 

 the trees with a solution of whale-oil soap, made in the pro- 

 portion of two pounds of the soap to fifteen gallons of water. 

 As the insects undergo their transformations mostly upon the 

 trees, in a loosely netted cocoon, secured among the half- 

 eaten leaves or affixed to the limbs, many of them may be 

 destroyed in the chrysalis state, by gathering and crushing or 

 burning their cocoons before the insects begin to emerge in 

 the miller form. Attempts may be made with some advan- 

 tage to destroy the eggs, by scraping the bark, or scrubbing 

 it with stiff brushes, or by applying thereto a wash of strong 

 potash water. 



A large proportion of the chrysalids, sent to me by Dr. 

 Gardner, failed to yield any moths, having perished in this 

 state probably in consequence of being previously preyed 

 upon by internal parasites. In fact, two kinds of parasitic 

 insects have been obtained from them. One of these is a 

 small ichneumon fly, described by Mr. Say, in the first vol- 

 ume of the Boston Journal of Natural History, under the 

 name of Cryptus conquisitor ; the other, a smaller and much 

 rarer insect, was described by Mr. Say in the Appendix to 

 the second volume of Keating's Narrative of Long's Expe- 

 dition, under the name of Chalcis ovata. For the characters 

 of these species, which would too much increase the length 

 of this long communication, the curious reader will please to 

 consult the works above named. 



Cambridge, Mass., August 8, 1855. 



