212 THE ENTOMOLOGIST. 



B. Nymph of Mschna cyanea. 

 Captured Jan. 19th, 1900. 

 Eestored to water Jan. 24th for 4 hours. 



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Feb. 8th „ 20 „ 



On February 8th A and B were put together and kept out of 

 water until March 8th. They were then finally restored to the 

 water, and, after appearing somewhat lethargic for about an 

 hour, recovered perfectly, and fed freely. 



On March 16th I received some specimens of Erythromma 

 naias, kindly sent me by Mr. Lucas ; one of these was kept out of 

 water, in similar conditions to the jE. cyanea mentioned above, 

 from March 16th to April 16th, and appeared quite well when 

 restored to the water ; and, curiously enough, during the time of 

 enforced fasting the nymph cast a skin, becoming, however, 

 slightly smaller, viz. from 27 mm. to 25 mm. in length. The 

 change of skin occurred on April 7th. 



It will be seen therefore that both these species are able to 

 live a month at least out of water. As to whether the after 

 development is affected I cannot say, as the nymphs were mixed 

 with others, and undistinguishable ; but they did not appear to 

 suffer in any way. 



Four nymphs of Agrion puella were also kept under obser- 

 vation. One of these apparently got tired of the experiment 

 after three weeks, and wandered off, and was lost ; but the other 

 three were kept thirty-three days out of water, and appeared 

 none the worse for it. 



The power of fasting possessed by the nymphs is connected, 

 I suspect, with the vexed question as to the time passed in the 

 nymphal state. To give an instance : of several nymphs of Mschna 

 cyanea caught in January last, all of which were of about the 

 same size, viz. 20 mm. long, one had not changed a skin by 

 April 15th, and had not grown at all ; another had cast several 

 skins by the same date, and was twice the length, viz. 40 mm. — 

 a big nymph. I have now (June 8th) five of these nymphs just 

 ready to emerge ; but the small one referred to grows very slowly, 

 and does not look like being ready to change this season. 



May I mention, in reply to the query of Mr. Lucas, that when 

 I said that the majority of my specimens of M. cyanea came out 

 at night, I meant, not early morning particularly, but any time 

 from late evening to midnight, and from midnight to early 

 morning — an inconvenient habit for the photographer. I have 

 many times covered up the nymphs just ready to emerge, in 

 hope of inducing them to believe that darkness had really 

 arrived ; but I do not remember to have been successful in de- 

 ceiving the nymphs, so as to persuade them that night had come. 



Southleigh Vicarage, Witney, Oxon : June 8th, 1900. 



