114 BRITISH BUTTERFLIES. 



movable during the life of the pupa, and certainly implying a capacity 

 for opening slightly, if required, during emergence. Similar relations 

 of the different parts of the pupa are more or less present in other 

 Lycaenid pupae, differing from those of the Piero-Nymphalids and 

 Papilios, and suggesting a closer relationship of this superfamily to 

 more primitive ones than occurs in other butterflies (Chapman). 



Stridulation of the pupa of Callophrys rubi. — Kleemann, in 

 1774 (Der Naturforscher, iv., p. 123), noticed that, coming from the 

 pupa of this species (that feeds on Spartium scoparium), one could, 

 when one placed the pupa near the ear, distinctly hear a cracking* 

 noise, but whence it proceeded and by what means it was produced, 

 he could not determine. Esper quotes this (Schmett. Eur., i., p. 281), 

 calling the noise, " a humming sound," and so does Werneburg 

 (Beitrage, etc., i., p. 370), but no further observations seem to have 

 been made till 1877, when Schilde (Stett. Ent. Ztg., xxxviii., 

 p. 86) recorded some original observations as follows : Turning some 

 25 pupae of C. rubi upon a sheet of paper, he distinctly heard a peculiar 

 noise which came from the pupae. Watching them closely and 

 separately, he satisfied himself that the pupa of C. rubi, without any 

 perceptible motion, produces a slight short chirp, but, in order to hear 

 the sound distinctly and continuously, it is best to place a number of 

 the pupae together. In the evening, he says that he could distinctly 

 hear the chirping of the 25 pupae through the gauze, which covered the 

 vessel in which they were. He then writes : " On examining the pupae 

 individually, I found that, in the thicker ones, which were probably 

 $ s, I could hear the sound distinctly, whilst in the more slender ones, 

 which were probably $ s, I could hear nothing. I also noticed that, 

 after a copious watering of the earth on which they rested, all the 

 pupae were mute, but as soon as they were dry they began to chirp 

 again. My first idea was that this sound was an expression of 

 uneasiness, because a slight disturbance of their repose, by touching or 

 blowing on the pupae, seemed to make the chirping demonstration 

 more general, but the silence of the pupae suggested another cause, 

 viz., that the sound arises from the air being pressed and drawn in 

 through the tracheae on the abdomen and behind the eyes ; perhaps, 

 if the dense clothing of fine bristles is for the purpose of conducting 

 moisture inwards, it is possible that, with the same object, a more 

 lively respiration takes place when the pupa is dry, but, on the other 

 hand, ceases when this is no longer the case." He adds that, "in 

 individual pupae the noise sounds clearly, in short, quick ' tempi,' 

 almost as though a little stone were shaken in an empty pupa-skin. 

 This impression is produced all the more readily, because, if one moves 

 the pupa quickly backwards and forwards close to the ear, the sound 

 is the more distinctly audible." A similar sound made by the pupa of 

 Bithys quercus, was observed in July. 1880, and reported by Parish 

 (Ent., xiii., p. 186). 



Time of appearance. — This common little butterfly is a most 

 interesting creature. Hybernating in the pupal stage, its time of 

 appearance is largely determined by the kind of spring weather to 

 which its particular habitat may be subjected, and, whilst it is absolutely 

 a single-brooded species, at least in central Europe, a continuance of 

 cold weather in a certain season may cause its time of emergence to be 

 spread over a long period, and a comparison of different years may 

 give an idea of double-broodedness. Gauckler states that the pupa 



