SCIENCE-GOSSIP. 



DRAGON-FLY GOSSIP. 



BV W. H. NUNNEV. 



'npHE accompanying figures are reproductions 

 from microphotos lately sent me by Mr. J. 

 Mearns of Aberdeen, and, from the comparative 

 aspect of larval species, are deeply interesting. 

 Fig. I. represents a caudal fan of the larva-nymph 

 of Pyrrliosoma minium, which larva was somewhat 

 minutely described by me in Science-Gossip for 

 September (vol. i., N.S., p. 148), 1894. A curious 

 thing with reference to this species is that the 

 nymph when dead, from natural causes, and slightly 

 decomposed, assumes much of the scarlet tint 

 possessed by the perfect insect. 



morphosis. This month of -May, being so far hot, 

 has produced to me one small male of L. ^-maculata, 

 which emerged on the 8th about sundown. This 

 is the first time I have observed the change 

 to imago state in this species, and in none 

 other have I so well been able to observe the 

 development of the imaginal labium and appendages 

 from the " mask" of the nymph. The process is 

 marvellous, and needs to be watched with extreme 

 patience and care to enable a good mental grasp of 

 the details to be obtained, but is well worth the 

 trouble. The hinged portion of the nymphal mask 



Tail-Fans of Dragon-Flv Larva-Nymphs. 

 Fig. r, Fan of PyrrJwsoma miiiimii ; Fig. 2, Micronympha pumilio ; Fig. 3, M. elcgaiis. 



The Other two figures are of the caudae of species 

 of Micronympha. The difference in general shape 

 and the characteristic branching of the tracheae are 

 very noticeable and, seen apart from the species to 

 which they belong, they hardly seem to be 

 congeneric. It is difficult to conjecture the reason 

 for such difference in these lamellae, as shape can 

 have here but little to do with function. 



For many months past I have had under observa- 

 tion larvas-nymphs of all groups, representing many 

 species ; of these five are now in my rearing glasses. 

 Probably owing to the colder climate of the north, 

 the larvae of ^schnae and Libellulae from Scotland 

 are far more vigorous and pugnacious than their 

 southern forms. Further, I think I am justified in 

 saying, they attain a larger size before the final meta- 



merges, I believe, into the hypopharynx of the 

 imago, whilst the centrally divided labium, at first 

 puffy and of no particular shape, gradually 

 broadens out into the noticeable lower lip and 

 palpal lobes of the imago, approaching the maxillae 

 and mandibles until occupying practically the same 

 relative position as the mask of the larva. 



It is curious how few parasites have been re- 

 corded in connection with dragon-flies ; Polyncnu 

 natans attacks their eggs, flukes thrive in the 

 intestines of the larva;, Acari infest the wings of 

 some perfect forms, and I have found a Dipteron. 

 belonging to the family Borborids, associated 

 with an adult ;Eschna, a hitherto unrecorded 



fact. 



25, Tavistock Place, Bloomsbuiy, London. W.C. 



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