84 BRITISH ICHNEUMONS. [ Bassus 

feed exclusively on different species of Aphis.” Early in September, 1907, 
I found it swarming on reeds at Southwold, which were infested by myriads 
of the Aphid, Hyalopterus arundinis, Fab., and I captured one female in 
the act of investigating the leaves they were on, though not ovipositing. 
Bankes has, however, kindly given me a female, bred by him in the Isle 
of Purbeck in 1902, together with the Syrphid puparium from which it 
had emerged; the latter is entirely identical with others from which I 
have raised Syrphus balteatus, probably the usual host of this ubiquitous 
insect. 
2. tricinctus, Grav. 
Bassus albosignatus, var. 4, Gr. I. E. iii. 345, ¢. B. tricinctus, Gr. lib. cit. 
351, ¢; Morl. Trans. Ent. Soc. 1905, p.425, g ?; cf. Brisch. Schr. Nat. Ges, 
Danz. 1878, p. 111. B. flavolineatus, Zett. I. L. i. 378, excl. ? et var. (71ec 
Grav.). B. nemoralis, Holmgr. Sv. Ak. Handl. 1855, p. 354; Voll. Pinac. pl. i, 
fig. 3; Thoms. O. E. xiv. 1469, ¢ 9. 
A distinctly punctate species with the abdomen not or obsoletely red- 
marked. Mouth, clypeus, facial orbits and in ¢ epistoma, marks before 
the concolorous tegulae, scutellum apically or entirely, and hind tibial 
band, white. Legs totally red with only the hind tarsi, and remainder of 
their tibiae entirely, black. ¢ with scape beneath and anterior coxae 
entirely flavous; areola very small and irregular. Three first segments 
transversely impressed and (in form typ.) apically red ; basal segment sub- 
quadrate, rugosely punctate and impressed before the centre, with discal 
carinae extending nearly to the anteapical impression. Length, 4—55 mm. 
Holmgren’s variety zemoralzs differs from the type form only in having 
the abdomen immaculate black; it is much commoner with us than that 
with the incisures red, as was described by Gravenhorst. 
Smaller and less stout than 2. albosignatus with the frons very finely 
and more sparsely punctate, the areola irregular, the basal segment 
slightly broader and not apically white. From all the other species of 
this genus, except the rare B. multicolor, it is at once known by its entirely 
pale, red or flavous, anterior coxae and the bicoloured hind tibiae. 
This is an extremely common species and | have heard of it or seen it 
from Nunton in Wilts and Botusfleming in Cornwall (Marshall), Shere 
(Capron), Plymstock, Croydon and Hunstanton (Brunetti), Redland and 
Bristol (Charbonnier), Hastings (Esam), New Forest (Miss Chawner), 
Tarrington, Hereford (Yerbury), Chatham (Garde), Guildford (Butler), 
Askrigg in Yorks and Banchory in Scotland (Elliott), Tostock, Benacre 
and Bungay (Tuck), Kilmore in Ireland, Whitby and Blackheath (Beau- 
mont), Isle of Mull (Tomlin), Isle of Portiand and Barmouth (Bradley), 
Gullane and Edinburgh (Evans), Basingstoke (Hamm), on hemlock in 
Wigtonshire (Gordon), Blackburn (Bowdler), Kings Lynn (Atmore), Ex- 
minster and Plym Bridge (Bignell). It is frequently taken by sweeping, 
but more usually at the heads of both Heracleum and Angelica, quite as 
often in their seeding, as in their flowering condition, and is on the wing 
from zoth May to 14th September. On 24th June, 1899, I took a female 
investigating a thistle-stem (Onopordon acanthium), covered with Aphis 
cardut, Linn., on the bank of the Gipping at Blakenham, with several 
Pemphredon and Pimpla graminellae (cf. Ichn. Brit. iii. 60); and on 26th 
July, 1904, one was probing the stem of Heracleum sphondylium in an Ips- 
wich garden with her antennae, it walked over the flowers heedlessly, but 
Was very interested in Aphis hAieraci’, Kalt., which covered the plant, 
doubtless in search of the larvae of some Syrphidae, from which family I 
