542 



Mr. C. L. Witliycombe's Notes on 



grey. A faint darker lateral line may be present. It should be 

 noted that Avhile a newly-moulted larva may be very dark in colour, 

 a full-fed one is often of pale dove-grey. 



As will be seen, this larva is very distinct from all those 

 previously mentioned, and can easily be identified. How- 

 ever, nervosa has probably a similar larva. 



For pupation an elongate, loosely woven cocoon of white 

 silk is spun. One noticed was 6-5 mm. long x 2-5 mm. 

 broad, but this is rather large. In summer the larva 

 pupates and emerges in two or three weeks after spinning, 

 but later in the year it remains curled up within the cocoon 

 and winters as a larva. A warm spell occasions the change 

 to pupa, and the imago follows in due course. Once the 

 pupa is disclosed, the imago appears in a few weeks. Thus, 

 one pupated 25/2/21 and emerged 31/3/21 = 34 days at 

 an average temperature 50° F., a second pupated 20/3/21 

 and emerged 12/4/21 — 23 days at an average temperature 

 52° F., and a third pupated 4/3/21 and emerged 4/4/21 = 

 31 days at an average temperature 52° F. 



Little need be said of the habits of the larva except that 

 it is very voracious, and will take any species of aphid. 

 Commonly it may be found on beans preying upon the black 

 Aphis rumicis L. Others have been found feeding upon 

 coccids, Pulvinaria hetulae L., on vine, etc. All stages of 

 Aleurodids and Psyllids, besides various mites, are taken 

 as food. 



Boriomyia nervosa Fabricius, 



Wing expanse 14-18 mm. Veiy like B. subnehulosa, but as a rule 

 of a more variegated appearance. Males are easily determined by 

 the genitalia, but females are frequently indistinguishable from 

 subnehulosa. A venational difference was indicated by Brauer (3), 

 but this is not constant. 



One larva has been seen, taken by sweeping among 

 nettles. It was considered at the time to be subnehulosa, 



