^B^^jete^sail'Ki
BRITISH BLOOD-SUCKING FLIES
spindle-shaped, moderately deeply striated, and has only six retractile pseudopods
nistead of the usual eight on the front margin of each segment from the
fourth to the tenth. The ground colour is greenish, the body wall transparent,
and the internal organs readily visible.
C. caecutiens is found in all parts of Europe from Sweden to Corsica.
Chrysops quadrata Meigen
(Plate 17)
The basal half of the upper surface of the abdomen in the male of C. quadrata
shows a considerable amount of paler coloration at the sides, although the
median quadrate black spot on the second segment, a continuation of the black
area of the first, is very much larger than in the female, and nearly reaches the
hind margin. As in the female the hinder portion of the third segment and
sometimes that of the fourth as well is conspicuously yellow. The median
black spot on the second abdominal segment of the female is variable m shape
as well as in size, being sometimes nearly square, sometimes more or less
distinctly cordate. Frequently, especially when more or less quadrate, it is
connected with the blotch on the first segment, but in very many cases it is
separate.
So far as it is possible to judge from the not very extensive series of British
representatives of this species at present contained in the Museum, C. quadrata
varies from 7-5 mm. to 9 mm. (males) or 10-5 mm. (females).
This species is not often met with, especially in the north, though according
to Verrall (1909, p. 431) it is " widely spread over the southern and midland
counties." Goffe (1931, p. 55) says : " It is very common in the New Forest,
particularly in the district surrounding Matley Passage and Denny Lodge."
Verrall also states that C. quadrata was taken at Aviemore, Inverness-shire, in
July 1899 by Lt.-Col. Yerbury. There is no other Scottish record, and none
from Ireland.
Dates of capture of the Museum specimens range from June 24th to September
1st, the earliest date mentioned by Verrall being June 7th.
Males of C. quadrata, with others of caecutiens and relicta were among the
male Tabanidae taken by Jones (1922, pp. 40-41) drinking on the wing from
a muddy pool in Rhinefield Enclosure, Lyndhurst, New Forest. Goffe (1935,
p. 102) also found large numbers of males of this species between June 15th
and August 2nd, in the Lyndhurst-Beaulieu district of the New Forest. '' They
were observed to fly in rapid evolutions very close to the water for a few seconds,
touching the water at intervals of a second or so ; the movements rather reminded
one of the small whirligig beetles of the genus Gyrinus Linn. They
were also found resting on grass, etc., overhanging the water." Unlike Mr.
Jones, Mr. Goffe did not see a single caecutiens.
The pupal stage, according to Lundbeck (1907, p. 96), is passed in moist
sand near water.
Chrysops quadrata occurs all over Europe, Lundbeck gives it as "not
uncommon " in Denmark.
BRACHYCERA—TABANIDAE 81
Chrysops relicta Meigen
(Plate 18)
In the male of this species the basal half of the upper surface of the abdomen
is conspicuously yellow on each side, the second visible segment exhibits a
large, black, median blotch which is bifurcate posteriorly, and the middle and
hind tibiae are reddish-yellow. In the female illustrated in the plate the wings
are in a resting position, and the spots on the second segment of the abdomen
are somewhat obscured, the pale lateral extremities of the first two segments
being scarcely distinguishable. In reality, when the wings are clear of the
body the pale areas are very conspicuous. The markings of the male abdomen
are similar to those of the female, but the sides of the basal portion are deeper
in tone, and the pale triangles much less distinct.
The plate fails to show the markings of the upper surface of the thorax as
clearly as could be wished. In the female there are a pair of fairly broad,
olive-grey, longitudinal stripes, one on each side of a dark median line, and fused
together at their anterior ends, where they appear bluish-grey ; a broad, dark
olive-grey or iron-grey longitudinal stripe outside these to the right and left ;
and a greyish-olive or deep olive-grey lateral border on each side, clothed with
shining yellow hair.
Full details of the coloration and markings of the eyes in this species,
with a figure of the eye in the male, are given by Verrall (1909, p. 432, 434,
fig. 247).
British examples of Chrysops relicta in the Museum measure from 8 to
11 mm. in the male, and from 9 to 11 mm. in the female.
In the British Isles C. relicta is generally distributed and sometimes locally
common, from South Devon to the north of England, besides being found in
Wales and Ireland. Goffe (1931, p. 57) says that it seems to be most common
round watery places on old heathlands, and that it is stated to be more common
in Scotland than C. caecutiens.
The dates of capture of the specimens in the Museum range from May 24th
to August 31st, but at Reading the late Mr. B. D. Burtt took both sexes as
late as September i8th. The last-mentioned were taken on water mint,
where the male was feeding on the flowers, and on August 24th, at Bulmersh
Park, Reading, Mr. Burtt found males of relicta swarming everywhere on the
lake margin, resting on the flowers of the water mint, on rush leaves, and on
every water-lily leaf. On June 29th and July 2nd, 1922, in Rheidol Valley,
Aberystwyth, males were taken by the same collector on water dropwort
{Oenanthe sp.).
Lundbeck (1907, p. 97) states that the pupa of this species is some 13 mm.
m length, and in Denmark has been found in sand at Fures Lake. Beling
met with three pupae of C. relicta in sand at the edge of a small brook in a
meadow in the Harz district in North Germany. He describes the pupa as
dirty brownish-yellow in colour, 12 mm. in length and 3 mm. in breadth.
Chrysops relicta occurs over the whole of Europe, and in Germany, according
to Krober (1920, p. 125), it is probably the commonest species of its genus.