THE ENTOMOLOGIST 



Vol. XXXIIL] OCTOBER, 1900. [No. 449. 



SOME ADDITIONAL NOTES ON MSCHNA CYAN E A. 

 By Rev. Arthur East, B.A. 



Now that the dragonfly season is drawing to a close, the 

 Editor will perhaps allow me to offer a few notes on Mschna 

 cyanea, supplementary to those which appeared a short time 

 since [ante, p. 211). It is well known that during the final 

 change of this nymph the head and thorax are thrown right back, 

 and that the emerging insect hangs suspended head downwards 

 from the old nymph skin. No observations, however, seem to be 

 recorded as to the manner of the previous changes — those, namely, 

 which take place under water — and it is surprising how seldom 

 one catches the nymph in the act of changing : the pale green 

 object always seems to have /usi finished. However, several have 

 been seen this season, and the process is as follows. 



The nymph seems to be much extended, the joints of the 

 abdomen appearing stretched, and especially the head seems to 

 be extended far forward. Soon a split occurs down the middle 

 of the back of the thorax, and the pale green body is extruded 

 straight forward by muscular action of the abdomen alone, the 

 legs taking no part in it, nor is the body bent at all in any 

 direction. When the whole nymph has projected itself out of 

 the old skin, with the exception of the last two segments, it rests 

 for a short while (two or three minutes, perhaps), the legs all 

 parallel with one another and with the abdomen, and reaching 

 slightly forwards, but touching nothing. Then the nymph gently 

 takes hold of the support it is on with all six legs, gives a slight 

 wriggle with the abdomen which shakes it free from the cast 

 skin, and is ready in half an hour to begin feeding again. 

 The whole process is very short, and from the first appearance of 

 a split in the nymph skin to the skin's final rejection it only takes 

 a few minutes — seven or eight perhaps. 



The following observations (although incomplete) will, I hope, 



ENTOM. — OCTOBER, 1900. Z 



