Plesina. 255 



on Fiinen at Odense; in Jutland at Sønderborg, Hejls, Jelling and 

 Aalborg and on Bornholm at Rønne and Allinge; the dates are 

 5/ g — 30^^ It occurs in and at woods on flowers and leaves of biishes; 



Fig. 70. Wing of M. roralis ?. 



it vibrates its wings when walking. Mr. E. Hoffmeyer bred it from 

 egg-masses of Epeira cornuta, and lie commimicated to me that the 

 larva was not imcommon in this way; the imago appeared on i/,. 



Geographical distribution: — Europe; towards the north to 

 middle Sweden, and in Finland. Also occurring in North America. 



45. Plesina Meig. 



Smallish or medium sized, black species, with a little pruinosity, 

 and with dark marked wings. Head slightly broader than thorax, a 

 little convex behind, especially below, and here somewhat puffed 

 out. Frons about as broad as or a little narrower than the eye, equal 

 in both sexes, not protruding but rounded in profile. Jowls nearly 

 half as broad as the eye is high. In both sexes ocellar and inner vertical 

 and two orbital bristles. Postocellar bristles none or small, but distinct 

 occipital bristles. Behind postocular bristles black hairs. Frontal 

 bristles reaching to insertion of antennæ, above an outwards directed 

 bristle in both sexes. Clieeks bare. Vibrissæ slightly ascending. Eyes 

 bare. Epistoma not retreating. Oral cone and proboscis short, labella 

 relatively large; clypeus short, horse-shoe-shaped. Palpi small and 

 thin, thread-like, slightly dilated at apex. Antennæ inserted below 

 middle of the eye, short, third joint somewhat longer than second; 

 arista slightly pubescent. Thorax rectangular; three postsutural 

 dorsocentrals ; one or no præsutural and a præscutellar pair of acrosti- 

 chals ; one or two posthumeral bristles ; three intraalar bristles or the 

 middle one sometimes wanting. Scutellum with two marginal bristles 

 on each side, the apical crossing; a weak basal bristle also sometimes 



