HYMEXOrXERA. 421 



all sides, and an oblong oval cavity is thus formed, and is after- 

 wards lined with a sticky and glossy substance, to which the 

 grains of earth closely adhere. Within these little earthen cells 

 or cocoons the change to chrysalids takes place ; and, in six- 

 teen days after the descent of the slug-worms, they finish then- 

 transformations, break open their cells, and crawl to the sur- 

 face of the ground, where they appear in the fly form. These 

 flies usually come forth between the middle of July and the 

 first of August, and lay their eggs for a second brood of slug- 

 worms. The latter come to their growth, and go into the 

 ground, in September and October, and remain there till the 

 following spring, when they are changed to flies, and leave 

 their winter quarters. It seems that all of them, however, do 

 not finish their transformations at this time ; some are found 

 to remain unchanged in the ground till the following year; so 

 that, if all the slugs of the last hatch in any one year should 

 happen to be destroyed, enough, from a former brood, would 

 still remain in the earth to continue the species. 



The disgusting appearance and smell of these slug-worms 

 do not protect them from the attacks of various enemies. 

 Mice and other burrowing animals destroy many of them in 

 their cocoons, and it is probable that birds also prey upon 

 them when on the trees, both in the slug and the winged 

 states. Professor Peck has described a minute ichneumon- 

 fly, stated by Mr. Westwood to be a species of Enci/rtus, that 

 stings the eggs of the slug-fly, and deposits in each one a 

 single egg of her own. From this, in due time, a little mag- 

 got is hatched, which lives in the shell of the slug-fly's egg, 

 devours the contents, and afterwards is changed to a chrysalis, 

 and then to a fly Hke its parent. Professor Peck found that 

 great numbers of the eggs of the slug-fly, especially of the 

 second hatch, were rendered abortive by this atom of existence. 



Ashes or quicklime, sifted on the trees by means of a sieve 

 fastened to the end of a pole, was recommended, by the late 

 Hon. John Lowell, of Roxbury, for the destruction of the slugs; 

 and it is found to answer the purpose. It is probable that Mr. 

 Haggerston's almost universal remedy may prove to be still 

 more effectual. 



