252 
LYCAENIDAE 
some species of the Lycaenids, is very rare in M. avion. A 
dwarf form with a wing expanse of only about 28 mm. and 
of dull colouring is of frequent occurrence. The blue is of less 
extent and duller, the markings paler, the marginal borders 
broader, and the costal margin of tile fore wing darker than 
in normal specimens. Probably this dwarfing and dull 
colouring may result from the larvae being associated with 
unsuitable species of ants, possibly the small yellow ant 
(Donisthorpea flava ), which is known to be an unsuitable host, 
may be the cause. Both Myvmica scabrinodis and M. laevin- 
odis are equally suitable as hosts. I have frequently seen 
M. avion laying its eggs upon Thyme growing on the nest 
hillocks of D. flava, but very careful examination of scores 
of D. flava nests failed to reveal a single larva of M. avion 
in the localities where M. avion was most abundant. D. flava 
and M. scabvinodis very frequently nest side by side, both 
occupying the same hillock, one side M. scabvinodis and the 
other D. flava ; it is, therefore, likely that M. avion larva at 
times takes up its abode in the nest of D. flava, resulting in 
the production of a dwarf form of this butterfly. 
Genus LYCAENOPSIS, Felder and Felder , 1865 
THE HOLLY BLUE 
Lycaenopsis avgiolus (Linn., 1758). 
(Plate XVIir, facing page 205) 
Previous to the beginning of the present century, the Holly 
Blue was only fairly plentiful in the southern counties, but 
from 1900 it gradually became more abundant each successive 
year, until it appeared in profusion, especially in suburban 
gardens, and remained in undiminished numbers until 1931. 
After which time it rapidly decreased and became compara¬ 
tively scarce, probably due to some unfavourable weather 
conditions during its pupal existence in the winter or when in 
the young larval state in the autumn. But during the year 
1934, it again became plentiful in all its usual haunts, and the 
second brood was unusually abundant generally, occurring 
also in districts where it is usually scarce. 
