110 BRITISH ICHNEUMONS. [ Homocidus 

Antennae reaching beyond thorax, black and apically subattenuate; ¢ 
with scape alone pale beneath. Thorax with mesonotum subnitidulous, 
densely punctate and bearing lateral elongate sublinear flavous marks ; 
mesosternum laterally closely and coarsely punctate, in @ sometimes 
pale-lined, speculum glittering ; metathorax subrugose with the petiolar 
area apically indicated and lateral costae obsolete. Scutellum black or 
with, at most, its apex pale. Abdomen hardly half as long again as 
thorax, usually broadly red centrally, of Q elongate-oval and apically sub- 
compressed ; the basal segment hardly longer than apically broad, scab- 
riculous with no discal carinae; second scabriculous but not basally strio- 
late between the inconspicuous thyridii, remainder smoother to anus. 
Legs not slender, red; coxae and trochanters black with the anterior 
apically in 9,or mainly in @, stramineous ; hind tibiae immaculate, their 
tarsi nigrescent. Wings subhyaline ; stigma infuscate and basally paler, 
emitting the radial nervure almost beyond its centre; areolet oblique 
and subsessile; nervellus a little antefurcal and intercepted below its 
centre. Length, 4—5} mm. 
The abdominal rufescence is very variable in extent: all the segments 
may be black (nigrifarsus/, segment three at base and apex only red 
(rufonolatus), segment three entirely with apex of second and base of 
fourth red (type form), or segments two to four and apex of first red 
(elegans, Desv.) ; the @ rarely has segments two and three red with an 
infuscate central fascia and the fourth basally white, its face too is 
occasionally black-marked (piccfans/. 
The form with black abdomen will at once be recognised from species 
of the dimidiatus-group by its red tibiae and, at most, apically pale scu- 
tellum ; from its immediate allies this species is easily distinguished by 
its evenly emarginate vertex, subnitidulous and obviously punctate 
mesonotum, entirely red femora and tibiae, and the coarse close punctura- 
tion of its mesopleurae; the @ may further be known by its black 
flagellum. Dalla'Torre follows Marshall in erroneously synonymizing 2. 
preitans with B. obscuripes, Holmgr.; I have seen Desvignes’ types in the 
British Museum and find they belong here. 
This is a widely distributed species throughout Scandinavia, Germany 
and France (Nantua in Ain and Nantes, Marshall). In Britain it is 
abundant on flowers from the middle of May to the beginning of October, 
though nothing is at present known of its economy, for we cannot 
imagine that either Bombyx quercus, which is much too large or Gracillaria 
phasianipennella, which is much too small, are likely hosts for the species 
of a genus known to be probably exclusively confined in their parasitism 
to aphidiphagous Diptera (cf Fitch’s record, Entom. 1881, p. 141). Never- 
theless, the former host is repeated by Bignell (Tr. Devon. Assoc. 1898, 
p. 500), who also captured this species at Shaugh Bridge on 15th May, 
Oreston, Whitsand Bay, Plym Bridge and Bickleigh in Devon. Devon- 
port in May (Garde); Cornworthy (Marshall) ; Hastings District (Esam) ; 
Deal (Sladen); Greenings (W. Saunders) and Shere (Capron), in Surrey ; 
Blackheath, on znd October (Beaumont); Felden in Herts (Piffard) ; 
Essex (Harwood) ; Bury St. Edmunds, Bungay and Southwold, in Suffolk 
(Tuck) ; Brundall, Eaton and Mousehold, near Norwich (Bridgman) ; 
Hunstanton (Brunetti) and West Runton (Wainwright), in Norfolk ; Can- 
nock Chase (Tomlin); Cornworthy, Botusfleming, Nunton in Wilts, 
Lastingham in Yorks, Bishops Teignton, and Bugbrooke in Northants 
(Marshall). I have found it frequently at Burnham Thorpe, in Norfolk, 
