SHOT-BORER BEETLES. 83 
scopic), &e., just what these Acari like. If it were my case, I should 
let them alone; but if you wish to destroy them, it will be rather 
difficult to do so while they are in the adult stage; chemicals are 
useless then, as they do not penctrate the hard shell; boiling water 
would do it at once if it could be conveniently applied without injuring 
the trees, but I believe that there is often a practical difficulty about 
this. If it cannot be done, a sticky material, such as soap, tar, &c., 
would catch large numbers, but not all. 
‘* When the creatures are in an immature condition, rather earlier 
in the year (probably about June), the ordinary paraffin and soap 
solutions (strong) would probably kill them if applied three or four 
times at intervals of ten days or a fortnight, so as to catch fresh 
batches as they hatch from the eggs (which are impervious to 
chemicals). 
‘Tf you wish to know the immature stage by sight, you will find a 
coloured illustration of it in my ‘ British Oribatide,’ Ray Society, 
plate v. figure 2. It is very different from the adult; but, as I have 
said before, my own impression is that the best thing you can do is 
to let these creatures alone.’”’—(A. D. M.) 
The family of the Oribatide, which are often known as “ Beetle- 
mites,’ because, in the adult stage, they have a hard skin (chitinous 
exo-skeleton) like beetles, are very small somewhat globular Acari, often 
black or brown in colour, and have eight legs. In their first condition 
(that is, after hatching from the egg) they are soft, and have only six 
legs. The O. lapidaria (of Lucas), mentioned above, is only about a 
third of a millimétre in length,* and dark brown, and usually, though 
not quite always, also shining in the adult state; in the preceding 
condition it is more of a diamond-shaped form, and “orange red 
varying to dark pink’’ in colour; in the first stage most of the 
Oribatida have little eclour. (See Mr. Michael’s work, previously 
quoted.) 
The above remarks on this fungus-eating ‘‘ Mite”’ are submitted in 
view of the possibility of it being in some degree a natural protector 
against increase of the ‘‘Shot-borer” or ‘‘Ambrosia’’ Beetles, by 
robbing them, for its own support, of the “ ambrosia fungus,’”’ on which 
they mainly feed. We cannot tell how this may be without further 
observations verified by an expert. Unfortunately I have not sufficient 
knowledge of these ‘‘ Mites’”’ in their early stages to make my identifi- 
cation trustworthy; but it may prove of some interest to mention 
that, about December 11th, on examining my few remaining specimens 
of saxeseni-infested Plum wood, I found a number of minute white 
‘‘Mites” straying about the ‘“‘ambrosia’’ patched surface of one of the 
saxeseni brood-chambers; and on the 14th I found them still there or 
* A millimétre is the twenty-fifth part of an inch. 
