( 501 ) 



XX. Notes on the Biology of some British Neuroptera 

 {Planipennia). By C. L. Withycombe. 



[Read October 18th, 1922.] 



Plates XXXVIII-XLIII. 



The present account is offered as a small contribution to 

 our knowledge of the earlier stages of British Neuroptera. 

 The writer is only too conscious of its incompleteness, but it 

 is to be hoped that further work will supply the omissions. 

 The Megaloptera, including Sialidae and Raphidiidae, also 

 the Mecoptera or scorpion-flies, must be treated of later 

 and separately. Excluding these two last-mentioned orders 

 from the Neuroptera, we have a very uniform grouping of 

 insects, although the Coniopterygidae stand somewhat 

 apart. 



As regards anatomy, this note is little more than a pre- 

 liminary one, being merely a summary of the more striking 

 characteristics of the order. External structure of imagines 

 has been almost entirely om.itted, as this is generally better 

 known. 



To avoid repetition, it is assumed when describing 

 individual larvae, that the general characters of larvae of 

 the family are known. Each description is therefore more 

 or less comparative, and points not mentioned are typical 

 of the family as a whole. It is to be hoped that, with such 

 brief descriptions, the drawings will facilitate identifi- 

 cation of the various species. With the exception of 

 Hemerobiid larvae, every species should be fairly easily 

 determined. Larvae of Hemerobius are very difficult to 

 identify. I have thoroughly compared the chaetotaxy of 

 every part of the body. It is constant in general plan 

 throughout all the species and where variable is not specific. 

 Pigmentation, arrangement of sclerites, etc., are likewise 

 useless characters. While, with a knowledge of habitat, 

 one may, after some experience, fairly certainly determine 

 a larva, the position is none the less very unsatisfactory, and 

 I regret that I am unable further to elucidate matters. 



Tables illustrating life-cycles have only been employed 

 to illustrate points of interest, or where such are considered 



TRANS. ENT. SOC. LOND. 1922. — PARTS III, IV. (FEB. '23) 



