REPORT ON THE LICHENS OF EPPING FOREST. 97
dwelling lichens, like cattle in a meadow. Michael, in his British
Oribatida 1883, describes numerous species of these mites as
haunting, and feeding upon, Lichens and specially mentions
four species as being "true lichen-loving creatures, seldom
found elsewhere," one species indeed (Oribata parmeliae) owes
its specific name to its lichen-habitat. Of the nymph of this
form (O. parmeliae), Michael notes that its bright-orange-yellow
colour resembles that of the lichen upon which it feeds (Physcia,
or, as it was formerly called, Parmelia, parietina) and suggests
that this may be a case of protective resemblance.
We have noticed other scarlet-and-black, oval mites (ap-
parently not of this family), with whose names we are not
acquainted, crawling in numbers over the thalli of lichens on
tombstones at Loughton and Theydon Bois, but whether ac-
tually feeding upon the plants could not be decided. Specimens
of Parmelia have frequently been seen by us with the thin green
cortical layer wholly or partially eaten away, possibly by mites,
leaving the white woolly medullary layer exposed.
Some Podurae, also, frequent lichens growing on walls.
Many moth-caterpillars feed on lichens on trees and walls ;
nearly all the "Footmen" moths (Lithosiidae) do so, for example ;
and we have several striking instances, both in the case of the
larva and of the perfect moth, of protective coloration and
resemblance to the lichens upon which the insects rest. A
very striking example is Moma orion, a common moth in many
parts of Europe, though rare in this country ; specimens of the
imago of which, at rest upon the lichen-covered bark which
they frequent, are exhibited at the Natural History Museum
at South Kensington ; other quite common British moths, as
Bryophila muralis. B. perla and Agriopsis aprilina, are
examples of this resemblance, and the ground tone of the colora-
tion of the wings of these moths is stated to vary according
to the prevailing hue of the lichens which they select for their
resting place.
One of the most remarkable examples of this protective
resemblance to lichens is that of the larva of the geometrid
moth, Cleora lichenaria, which feeds upon foliose lichens growing
upon tree-trunks and palings, and being of a green-grey hue
and possessed of two little humps on many of their body-seg-
ments, they so exactly resemble the lichens in colour and appear-