THE CHALKHILL BLUE 
229 
eggs. They fluttered slowly over the herbage carpeting the 
ground, which mainly consisted of Thyme, Rock-rose, and 
Horse-shoe Vetch, also other small chalk-loving plants and 
grasses. Among this varied growth L. coridon settled and 
crept about, sometimes for a distance of two feet or more. 
Now and again the butterflies stopped, lowered and curved 
the abdomen amongst the intermingled stems and deposited 
an egg here and there. Each female I watched acted in the 
same way. The eggs were laid singly, either on the stems of 
the Horse-shoe Vetch or any other plant stem close to the 
Vetch, often that of the Rock-rose. As the egg does not 
hatch until the following spring, the reason no particular plant 
stem is chosen is at once apparent, for all the plants die off 
in the winter, leaving only an entanglement of stems. The 
young larvae, upon emerging in the spring, must then 
necessarily search for the fresh young shoots of its proper 
food plant, H. comosa. 
The egg is very small, 0-50 mm. wide and 0*30 mm. high. 
It differs in shape from the eggs of all other British Lycaenidae. 
Instead of the usual sunken crown, the upper surface is flat, 
with only the micropyle sunken ; it is also higher in proportion, 
and the sides are almost perpendicular. The micropyle is 
very finely punctured, an irregular network pattern covers 
the crown and gradually increases in size until reaching the 
brim, where it develops into a beautiful lace-work pattern 
which is of bolder formation than that on other Lycacna eggs. 
The reticulations are united by large, prominent projecting 
knobs, varying in number from five to seven ; the sunken 
surface between is very finely granulated. The base is 
flattened. When first laid, the colour is almost white, which 
gradually changes to a slightly greenish-grey, remaining un¬ 
changed throughout the winter. Finally, just before hatching, 
the egg assumes a rather lilac tinge. The average period of 
the egg stage is 228 days. The larva emerges by eating a 
large hole in the crown of the egg. 
Larva. The little larva in its first stage feeds on both the 
upperand under surface of the leaves, but mostly on the latter, 
eating away the cuticle. It feeds chiefly at night, resting on 
the base of the stems during the day. When fully grown, after 
the fourth moult, it is 16 mm. long. Both the first and last 
