106 B R I T I S H BLOOD-SUCKING FLIES
B R A C H Y C E R A — T A B A N I D A E 107
counties, and Goffe (1931, p. 84) suggests that " it is probably overlooked in
south and middle England through its superficial resemblance to the common
T. bromius and T. maculico?-nis.
T. cordiger occurs throughout Europe, though it is not included in Lundbeck's
Danish list (1907). It has been recorded from Asia Minor, but Major
Austen believed that these records, and probably some of those from southern
Europe applied to a closely allied species, T. leleani Austen.
Surcouf (1921, p. 18) states that a larva of this species was found on March
4th, 1913, near Montpellier, S. France, in the stump of a poplar which had
just been felled. The wood, though soft and damp, was not yet rotten. The
larva was placed in a glass jar with some of the wood, but nothing else, and left
to its fate, and the adult insect appeared on June loth.
Tabanus autumnalis Linnaeus
(Fig. 41 and Plates 31 and 32)
Ranking fourth among British Tabanidae in point of size, T. autumnalis
is considerably smaller than the boviniis group, and at the same time distinctly
larger than any other British species. This fact, together with the very clearcut
pattern of three rows of pale triangles on the upper surface of the abdomen
makes this species unmistakeable.
The eyes of the male which exhibit above and in front a sharply circumscribed
area of large facets, are sparsely clothed, at least above, with minute
EIG. 4 1 .—T . autumnalis Linn. Head.
and very short pale hairs, distinguishable with difficulty under an ordinary
lens ; the eyes of the female are bare. In both sexes the eyes are devoid of
bands, and Brauer (1880, p. 192) describes those of the male as " black, iridescent,
the large facets grey."
Owing to the strong development of ferruginous ground-colour in the
abdomen of the male there is usually a well-marked sexual difference {cf. pis. 31
and 32). Occasionally, however, even in England, females of T. autnvinalis
are met with in which the abdomen has a conspicuous ferruginous tinge on
each side of its proximal half, and in Algeria and also in Cyprus females in
which the ground-colour of the abdomen is predominantly ferruginous are of
normal occurrence. In T. autumnalis found in Palestine there is no difference
in coloration between the sexes, the females having practically no trace of
black except at the tip, and a species described by Szilady as Tabanus brunnescens
was regarded by Major Austen as merely the Mediterranean form of
autumnalis.
The specimens in the British Museum vary in length from 16-5 to 20 mm
in the male, and 16-5 to 19 mm. in the female ; the wing expanse of a large
female may reach 37 mm., or nearly inches.
T. atdunmalis is predominantly a southern species, and practically all the
records are from the southern counties. Wingate, however (1906, p. 100),
records it from Durham (Bishop Auckland ?), and Harperley). It does
not appear to occur in Scotland or Ireland. Outside the British Isles the
species is found throughout Europe from Sweden to Corsica and Corfu, and
also occurs in Asia Minor, and north Africa.
A female in the Museum collections, taken at Gravesend on July 29th,
1906, by Colonel Yerbury bears the field-note : " apparently ovipositing in
wet mud at the side of ditch," and in Austria Kollar (1854, p. 533) found larvae
and pupae of this species in the banks and shallow places of the river Wien.
Lundbeck (1907, p. 130) states that pupae have been found in moist loam, and
that he has records of the adult from May 4th (which he considers exceptionally
early) to August 3rd.
Tabanus maculicornis Zetterstedt.
(Fig. 42 and Plate 34)
Along with T. cordiger and T. plebeius this species is one of the smallest
representatives of the genus.
In the male the lateral extremities of the second and sometimes also of the
third abdominal segment are tinged with russet brown, and the spots are smaller
and less strongly developed, otherwise the abdominal markings resemble those
of the female. The head of the male, which is relatively much larger than that
of the female, is deeply hollowed out posteriorly. The eyes in the male, though
usually described as bare are really sparsely clothed with very minute, erect,
pale hairs iust distinguishable under a hand lens, while the upper part of each
eye has a sharply defined area of larger facets. In life, according to Brauer
(1880, p. 197), the eyes of the male are "green, with a broad purple band at
the junction of the differently sized facets," while those of the female are " Green,
often with a coppery sheen, with a sometimes narrower, sometimes broader
purple band, which becomes less distinct towards the inner and outer margins."
The specimens in the Museum vary in length from 10-5 to 13 mm. in the
male and from 11-5 to 13-5 mm. in the female.
A s stated by Verrall (1909, p. 412) the male of maculicornis may be distinguished
from that of any other British species of Tabanus, except cordiger
and glaucopis, by the fringe of long hairs at the back of the head above. From