82 PLUM. 
females pitchy black, with a small amount of grey hairs, and rusty 
yellow antennx and legs; the males shorter, and of a paler brownish 
colour, and with longer hairs. ‘The female is about the eighth of an 
inch, the male somewhat less in length. They may be readily distin- 
guished from X. dispar (the only species which at present there may 
be occasion to distinguish them from here) by the female of dispar 
having the thorax (or fore body) large in proportion, and raised in the 
middle into a kind of hump, while the male, which is only two-thirds 
of the length of the female in this species, is remarkable for being 
much wider in proportion, and flat on the back. From all other 
species of Xyleborus it is considered that saxeseni=aylographus may be 
distinguished “ by the very regular rows of small but sharp teeth upon 
the declivity of the elytra.’’ (See ‘Ambrosia Beetles,’ referred to 
previously. ) 
In the course of correspondence on the ‘‘ Shot-borer”’ infestation, 
I was favoured by Mr. C. D. Wise with an observation of a coincident 
appearance of Mites (Acari) in such vast numbers on the stems of 
Plum trees infested by the ‘Shot-borer’’ that, on working up the 
subject, there seems to be good ground for hoping that these may be 
an important help in keeping both species of Xylebori in check. 
On July 380th Mr. Wise wrote that there were ‘‘ hundreds, even 
thousands”’ [of the creatures which at first were taken for little 
beetles], “‘ crawling about all over the stems of the trees, and these 
have spread to the trees adjoining.” <A few days later Mr. Wise 
mentioned that they were to be found in hundreds on the trees which 
were dying from attacks of the ‘ Shot-borer’’; and successive letters 
showed the vast numbers to which the infestation was increasing, as 
on August 7th ‘‘they are all over the stems of the trees in all 
directions”; and on the 12th, ‘‘the stems of our trees are covered 
with millions of them.” 
As it was exceedingly desirable to have an authoritative opinion 
what the hordes of creatures were doing, I suggested to Mr. Wise that 
we might venture to request Mr. Albert D. Michael (of Cadogan 
Mansions, Sloane Square, London, 8.W.) to assist us by identification, 
and on August 23rd he was good enough to write as follows :— 
‘‘The creatures sent are Acari, as Miss Ormerod correctly says; 
their name is Oribata lapidaria. They are very abundant, and probably 
the fine season has caused them to increase to an unusual degree. I 
do not think, however, that you need be alarmed at their presence ; 
they are vegetable feeders, but I never heard of their doing any 
practical harm to the trees or plants which they are found on; they 
feed chiefly on lichens and minute fungi, and will, I should think, help 
to keep your trees clean rather than injure them. I observe that the 
scraps of bark which you sent me are covered with lichens (micro- 
