IOO 



SCIEXCE-GOSSIP. 



LARViE-NYMPHS OF BRITISH DRAGON-FLIES. 

 By W. H. Nunney. 



(Continued ft 



T WILL now pass to the consideration of those 

 British groups and species about which we 

 have an} - information. As might be expected from 

 their habits, the number of known larval species 

 is small compared with that of known perfect 

 forms ; the future will probably enable us to 

 complete the history of each species. For this 

 purpose it is necessary to patiently trace the grades 

 of development, and to accurately describe and 

 figure them. They may probably all be reared in 

 ordinary aquaria, feeding them on blood-worms 

 and other aquatic life. Care must be taken, how- 

 ever, to exclude the larger water beetles. Separate 

 the species and do not overcrowd. The Odonate 

 larvae fall naturally into groups, in some measure 

 co-equal with those to which the perfect insects are 

 assigned, the poiymorphosis of certain of them, 

 notabhy of the members of the Libelluline and 

 Gomphine groups, rendering classification difficult. 

 There are two main groups, Libellulidae and 

 Agrionidae, each admitting several subdivisions. 

 The larvae of the typical group, Libellulidae, are 

 usually dull-coloured, frequently hideoush" ugly, 

 with an alarmingly aggressive appearance 

 culminating in the .Lschnae ; the Corduliinae alone, 

 however, in Britain approach the grotesque 

 hideousness of their foreign congeners. The 

 Agrionines are, on the contrary, usually brighter - 

 coloured and extremely delicate in contour. 



Standing at the head of the whole tribe of 

 dragonfLies is the sub-family Libellulina, the 

 members of which are unfortunately so little known 

 that characters for distinct individual recognition 

 ca nn ot at present be assigned them. Brauer has, in 

 his " Neuroptera Austriaca," given certain general 

 characters, w r hich, for w-ant of better and more 

 definite ones, must suffice. A close study of the 

 Libelluline larvae will probably result in the final 

 remergement of Newman's sub-genera into Linne's 

 original eclectic genus Libellula. 



Brauer notices three main variations from the 

 primary Libellula form, and the following species 

 of the group are, so far as I am aware, the only 

 ones that have, up to the present, come under the 

 observation of naturalists. 



The pre-eminent type, both of the dragonnies as 

 a whole and the Libellulina in particular, is 

 LIBELL ULA depressa. This species is short, and 

 is of a dark greyish-green or brown colour. The 

 spineless body, which is dilated about mid-way, is 

 entirely covered with minute hairs, some of which 

 spring from small tubercles situated in the middle 

 of the dorsal surface of the first segments. The 



om page 82.) 



wing-sheaths extend about half the length of the 

 body ; occasionally (as in all Libellulae, in which 

 tribe these are relatively longer than in iEschnae), 

 being quite as long. On the prothorax, above the 

 scales covering their bases, are two transverse oval 

 spiracles, such as are found normally in other 

 insects ranged along the sides of the abdomen. 

 The three upper caudal appendages are of nearly 

 the same length. The middle one is broad and 

 conical and the two inferior portions are curved 

 inwards at the point, and are slightly longer than 

 the others. The legs are occasionally faintly 

 spotted. This species occurs in stagnant water, 

 small ditches and streams, and is generally 

 distributed. 



LEPTETRUM quadrimaculatum, a member of 

 the second sub-group, has the head flat, the eyes 

 small and prominent, the body sparsely haired, the 

 tenth segment prominent and, with the others, 

 bearing oblique spines. This generalh' distributed 

 species occurs in stagnant pools, as well as running 

 water. 



ORTHETRUM cancellatum is one of the earliest- 

 described dragon-fly larvae. An old writer, Muraldt, 

 having published in a now rare Latin work, entitled 

 " Ephemeris Naturae Curiosorum," a loose general 

 description illustrated bj- a rude engraving. The 

 colour is whoil)- cinereous ; the e}-es are prominent 

 and of a clear bright green : the antennae are short, 

 thick and pilose. On both sides of the head 

 beneath the eyes are hairs, and the mouth is also 

 pilose. The abdomen is broad, tapering towards 

 the point, which is pilose, and is hairy at the sides. 

 Several blackish transverse lines ornament the 

 head, and the abdomen is distinctly marked along 

 the sides with blackish spots. There are also some 

 spots in front, and two lines on the tarsi. The 

 mask is two-thirds the length of the head. This 

 species is local and apparently confined to the 

 South. 



LEUCORRHIXIA pctoralis has the vertex of 

 the head hollowed. The eyes are small and pro- ■ 

 minent, the hairy body is slightly longer than 

 broad, and bears centrally above a row of bent 

 hairy teeth. The two last segments are without 

 spines, and the sides are spineless. Roesel figures 

 this species as Libellula vulgaia which it resembles. 

 No British locality can at present be given for the 

 occurrence pf this larva. 



SYMPETRUM vulgatum is, according to Brauer, 

 like the preceding species. I believe I have a 

 living nymph, but cannot at present speak with 

 certainty as to the specific characters. 



