NOTES TOWAEDS A LIFE-HISTORY OF POLYOMMATUS DONZELII. 313 



Notes towards a Life=history of Polyomraatus donzelii. 



By J. McDUNNOUGH. 



During a two week's stay at Pontresina, in the Engadine, in the 

 beginning of August, 1905, I had the good fortune to come across a 

 locality on the wooded slopes of Alp Languard, at a height of about 

 6200ft., where Polyommatus donzelii was very abundant. The males of the 

 species were generally somewhat worn, although a few freshly-emerged 

 specimens testified to the fact that the brood was by no means over; 

 the females, however, were nearly all in the pink of condition, and 

 quite as numerous as the males, a fact rather striking when one takes 

 into account the relative scarcity of this sex in some species of alpine 

 " blues." A reference to Wheeler's Butterflies of Switzerland revealing 

 the fact that the foodplant and larva were unknown, the opportunity 

 for clearing up the mystery surrounding the early stages of this 

 species, seemed too good to be lost. Numerous females were con- 

 sequently observed as they flitted about among the herbage, but they 

 were evidently not in an obliging mood, preferring to flirt with the 

 opposite sex, or sun themselves on the low shrubs, to performing the 

 more important task of caring for the reproduction of their species. 

 A search on some of the numerous plants growing in the neighbourhood, 

 had also no further result than to bring to light a large number of ova of 

 Aricia astrarche on Helianthemum nnlgare, and the hour of mid-day 

 compelled me to retrace my steps to the hotel without any definite result 

 being obtained. Towards 4 p.m., however, I again wended my way 

 up the slopes, and was almost immediately rewarded by seeing a 

 female of the desired species acting in a very business-like manner, 

 settling down time and again among the thick growth, as if engaged in 

 ovipositing. Marking a spot where it had last settled, I instituted a 

 careful search, at first without result, but finally under the curled up 

 margin of a dead leaf of Geranium pratense, a Lycaenid egg was 

 discovered, and I felt I had solved the mystery. A further examina- 

 tion of plants of this species, which was very abundant, produced 

 some 60 or 70 ova, and led to the following conclusion. The ova of 

 P. donzelii are deposited mostly singly, occasionally in groups of two 

 or three, under the dried and curled-up marginal tips of geranium 

 leaves, either on the growing plant or on leaves that have entirely 

 withered and died down. In only one single instance was an egg 

 discovered exposed on the upperside of the leaf. To make matters 

 still more certain, I enclosed several living females in a glass jar with 

 geranium leaves, and was rewarded in a few days with a small number 

 of ova, laid similarly to, and exactly resembling, those previously 

 found. The fresh leaves were invariably rejected, and only on those 

 partially dried were ova deposited. 



Being uncertain as to the duration of the egg stage, and having no 

 microscope with me, I immediately despatched a portion of the ova to 

 my friend Mr. J. W. Harrison, who very kindly undertook the descrip- 

 tion. This precaution, as it turned out, was not necessary, for, 

 with the exception of two larvae, which emerged during a very hot 

 spell in Zurich, on August 22nd, the ova remained intact, and an 

 examination, on my return to Berlin in September, showed the fully 

 developed larva curled up within the eggshell with the evident intention 

 of hybernating thus. It seems, therefore, fairly certain that P. donzelii 



