264 
LYCAENIDAE 
both the first and last segments are rounded and projecting, 
the former quite concealing the head, which is withdrawn 
into the segment while at rest. The head is rather small, 
shining and of a very pale ochreous-green. The segments 
are slightly humped dorsally. The whole colouring is a 
clear brilliant green, with slightly darker markings showing 
in certain lights, of which the oblique side stripes and dorsal 
lines are the plainest. The entire surface is sprinkled with 
tiny pure-white knobs on short stalks, resembling rough 
frosted glass, and in shape almost exactly like young un¬ 
expanded mushrooms. Short spinous, serrated hairs also 
cover the surface. The legs and claspers are closely united, 
almost touching at the base of each pair and occupying a 
medio-ventral line. 
The larvae of this species are myrmecophilous, though they 
do not possess a gland such as is present in the Lycaenas 
(vide M. arion). In the Berlin locality, where rutilus is still 
common, ants ( Myrmica rubra ruginodis) are in constant 
attendance on them, licking the sweet secretion that exudes 
from the skin of the larvae. The larvae are thus protected 
from their enemies by the ants, while the latter in turn get 
nourishment and pleasure from the secretion of the larvae. In 
this country, where some German rutilus larvae were kept 
free out of doors, ants (M. rubra laevinodis) visited them at 
once, showing that the ant had retained the habit though 
the butterfly had long since become extinct in England. The 
larval stage lasts only twenty-one days. This applies to the 
Continental form rutilus, of which there are two broods in 
the year. 
Pupa. The pupa averages about 11-50 mm. in length. 
It is dumpy and rounded. (Side View.) The head is slightly 
angular ; the thorax is convex ; the abdomen forms a complete 
curve to the anal extremity, which is flattened ventrally and 
clothed with cremastral hooks ; the ventral surface is almost 
straight. ( Dorsal View.) The head is rounded; the pupa is 
swollen across the thorax, and concave in the middle ; the 
abdomen is swollen and rounded. 
Directly after pupation, the colour is an ochreous-yellow, 
this changes through greenish and the markings gradually 
deepen. All the markings are clearly defined in ninety 
