26 APPLE-TRFNK BUPKESTIS— PARASITIC DESTROYERS. 



previously dwelt. On laying open one of these burrows I find 

 it is more than an inch in length and all its lower part is filled 

 and blocked up with the fine sawdust-like castings 

 of the worm. Thus when the worm is destined to lay 

 torpid and inactive during the long months of winter, 

 it has the forethought, so to speak, to place itself in a 

 safe and secure retreat, within the solid wood of the 

 tree, with the hole leading to its cell plugged up, so 

 as effectually to prevent any enemy from gaining 

 admission to it. 



Still, this worm is not able to secure itself entirely 

 from those parisitic insects which are the destroyers of so many 

 other species of its race, and which, as is currently remarked, 

 appear to have been created for the express purpose of preying 

 upon those species, in order to prevent their becoming excet-sively 

 multiplied. We should expect that this and other borers, lying 

 as they do beneath the bark or within the wood of trees, were so 

 securely shielded, that it would be impossible for any insect 

 enemy to discover and gain access to them, to moles.t or destroy 

 them. But among the specimens sent me by Mr. Barry, is one, 

 where the worm has been entirely devoured, nothing but its 

 shrivelled skin remaining, within and upon which are several 

 minute maggots or footless little grubs, soft, dull whi:e, shining, 

 of a long egg-shaped form, pointed at the tip and blunt in front, 

 their bodies divided into segments 'by very fine transverse im- 

 pressed lines or sutures. They are about one-tenth of an inch 

 long and 0.035 broad at the widest part. These are evidently 

 the larvae of some small Hymenopterous or Bee-like insect, per- 

 taining, there can be little doubt, to the family Chalcididje— the 

 female of which has the instinct to discover these borers, probably 

 in the earlier periods of their life when ihey are lying directly 

 beneath the bark, and piercing througii the bark with her ovipo- 

 sitor, and ■ puncturing the skin of the borer, drops her eggs 

 therein, which subsequently hatch and subsist upon the boier 

 eventually destroying it. These minute larvs were forwarded to 

 me under the supposition that they were injurious to the Apple 

 tree, whereas, by destroying these pernicious borers, it is evident 

 they must be regarded as our best friends. This fact illustrates 



