58 



some of these cases the eggs of the Bark-louse were sound and un- 

 touched; in others there were only a few of them sucked dry and 

 shriveled up; in others again, at one end of the scale the eggs would 

 be sucked dry and at the other end perfectly plump and sound, the 

 young Mites being stationed in the middle, as a mower stations him- 

 self between the standing grass and the swath that he has already cut ; 

 finally, in still other cases, nothing but the empty shells of the eggs 

 remained, and occasionally the hungry young Mites might still be dis- 

 covered among those empty shells, kicking and struggling in the snug 

 retreat that they had so ruthlessly desolated, as dogs sometimes fight 

 over a bone that has been already picked clean. 



Towards the spring, or late in the autumn, many of the scales, 

 some of them still containing a few eggs, may be observed to have 

 rather large, irregular, ragged holes in their external surface, quite 

 unlike the smaller, regularly-rounded holes, bored by Parasitic in- 

 sects when they make their escape from the shell of an insect of this 

 size that they have preyed on. Early in the autumn scarcely any 

 such holes are to be met with in the recently-formed scales. I sus- 

 pect that these ragged holes are the work of the Mites, and that, after 

 having sucked all the eggs dry, they feed upon the dry scale, until 

 hunger compels them to vacate the tenement and search out a scale 

 that has not as yet been preyed upon by their brethren. Dr. Fitch 

 mentions that he found a small Parasitic larva — which as usual bored 

 a small round hole to escape by — to be very common under these 

 scales. I have never met with any such larva ; but I have occasion- 

 ally seen scales, both of the Oyster-shell Bark-louse and of Harris's 

 Bark-louse, perforated by just such a small round hole as Dr. Fitch 

 describes; and I should judge them to have been made by a parasitic 

 four- winged Fly (Chalets family or Proctotrupes family.) 



Some of these Mite-larvae that were discovered in May, are de- 

 scribed in my Journal as being of a glassy-white color, six-legged, and 

 with the hind pair of legs placed as usual far backwards ; their bodies 

 oval, 2^ times as long as wide, and not at all hairy, and of about 

 the same length as the egg of the Bark-louse. Others, noticed about 

 the last of October, agreed pretty accurately with the above descrip- 

 tion. Others, again, found about the same time, differed in being 

 rather larger and more elongate — thrice, instead of 2^ times as 

 long as wide — and in having 8 distinct legs, the two hindmost pairs 

 separated by a very wide interval from the two foremost pairs. These 

 were probably the pupa form of the others. All of them had the 

 thorax separated from the abdomen by a transverse suture; and, as 

 is universally the case, so far as I have observed, with immature 



