146 BRITISH ICHNEUMONS. [ Mesoleius 


entirely black but usually of ¢ centrally, of 9 with third segment more 
or less broadly, deep red; basal segment twice longer than apically 
broad, laterally margined, with subcentral spiracles and distinct basal 
scrobes; terebra subexserted. Legs somewhat slender and elongate; 
red with coxae, trochanters, hind tarsi and occasionally femora and apices 
of their tibiae black; @ with the anterior coxae and trochanters partly 
flavidous ; femora not stout, calcaria elongate, claws stout with unguiculi 
nearly half as long again as the fourth joint. Wings with stigma tes- 
taceous-flavous, ¢ with radix and tegulae whitish ; basal nervure subver- 
tical, areolet small and petiolate; nervellus subopposite and intercepted 
nearly in its centre. Length, 8—9 mm. 
M. insolens has not hitherto been synonymised with this species, but it 
seems useless to attempt specific distinction between insects whose ? 9 
even Dr. Pfankuch says he cannot differentiate and the oculatissimus 
Thomson distirguished by no better characters than the generally larger 
size (mec Holmgr.), more strongly rugose-coriaceous pleurae, more 
evidently and sparsely punctate mesonotum, combined with black @ 
mouth and face, of AZ. zmsolens, of which he considered the entirely dis- 
tinct Z7yphon petulans and 7. evolans, Grav., to be varieties. The charac- 
ters of Thomson’s subgeneus Lagaro/fus appear hardly more than specific 
and I have, consequently, included them in my description of this species. 
The abdominal red colouration is very variable in extent, though always 
present; and the hind femora are not frequently black. 
In grassy places on umbells in August; Germany, Austria, Belgium, 
Holland, Sweden, France, Italy; it has once been bred from the larva of 
an unnamed species of Zenthredo by Brischke (Schr. Phys. Ges. Konig. 
1871, p. 82). ‘This is one of the most abundant species of the genus with 
us, though only occurring in the autumn; I have taken it nearly every 
year since 1893, from 11th August to roth October, on flowers of fennel, 
FHleracleum and angelica, as well as by sweeping reeds and grasses, at 
Brandon, Bramford, Covehithe and Barnby and Oulton Broads, Holton, 
Monks’ Soham and Henstead in Suffolk, and at Ryde in the Isle of 
Wight. It is recorded from the Isle of Man in 1869 (F. Walker), Hol- 
gate in 1881 (Wilson, Yorks. Nat. Union, 1882, p. 107), common in Nor- 
folk (Bridgman), and Bishops Teignton in Devon (Bignell). It was first 
found here at Netley in Shropshire (Gravenhorst, who named a male now 
in Mus. Brit.); London (Stephens, in whose coll. is one from Darenth). I 
have seen it from Hunstanton, 30th Sept. (Brunetti), Felden, 30th Sept. 
(Piffard), Cadney in Sept. and South Leverton in Notts, 6th Oct. (Thorn- 
ley), Lyndhurst in Sept. (Adams), Shere (Capron), Bungay on 3rd Oct. 
(Tuck), and Ousden 24th Sept. in Suffolk (Elliott), Whitby at end of 
August (Beaumont); Ballycastle, Co. Antrim in Sept., 1901 (Tomlin) ; 
Bonhill (Malloch), Park and Banchory in Kincardine in August (Elliott, 
EK. M. M. 1910, p. 37). From its frequency and autumnal appearance I 
would suggest A//an/us arcuatus as a probable host. 
9. fallax, Holmgr. 
Mesoleius fallax, Holmgr. Sv. Ak. Handl. 1855, p. 168; lib. cit. 1876, p. 42, 
é ?; Brisch. Schr. Phys. Ges. Konig. 1871, p.82; Schr. Nat. Ges. Danz. 1878, 
p. 87, ¢ (nec Thoms.). 
Head a little constricted posteriorly ; mandibular teeth of equal length, 
clypeus apically depressed and truncate ; mouth, clypeus and only @ face 
