A species of the western Palaearctic, type locality Northern Ireland, which breeds in tree-holes. It is found from the northern limits of oak (around 58°N) south to Algeria (around 35°N), and eastwards from Britain to Iran (Marshall, 1938; Stone et al., 1959). It is a univoltine species, overwintering in the larval stage, and with the adults being found in Britain from May to September, when the females have been reported as frequently biting in the daytime as well as in the evening (Covell & Shute, 1954).

Experimental material
Adult females were readily trapped attacking man at Wimbledon Common, Surrey, England (51°25'N) between 1900h and 2000h BST on 3 September 1968 (sunrise 0611h and sunset 1948h BST, daylength 13h37m) and these were used in experiments from 4 September. Further females were trapped at the same location on 9 September 1968, and these were used in experiments from 10 September. Field activity was primarily during the hour before sunset. Recordings were made with light-off at 2000h BST.

Experimental regimes
LD 4:20, nine females, recorded for days three to five.
LD 6:18, two females, recorded for days two to five.
LD 8:16, six females, recorded for days three to five.
LD 12:12, nine females, recorded for days two to four.
LD 14:10, two females, recorded for days two to five.
LD 16:8, six females, recorded for days two to four.
LD 20:4, three females, recorded for days two to five.
LD 22:2, six females, recorded for days three to five.

Results and discussion
The activity patterns are shown in Figure A8 below. The pattern in all eight regimes is dominated by the E' peak. It is clear that when L > 16h the E' peak falls progressively earlier as L increases, coming some 15-16h after light-on. In both LD 20:4 and LD 22:2 there is evidence of a burst of activity in the first 0.5h after light-off. In all regimes from LD 12:12 to LD 16:8 there is also a pronounced but shorter-duration M peak. Although in the mid-range LD regimes there is very little activity in the subjective night, there is evidence of increased activity some 8-12h after light-off when L < 12h. Parallel activity perhaps is seen also some 6h after light-off (i.e. 4-5h after light-on) in LD 22:2. It may be unusual for an Anopheles species but the pattern of activity of An. plumbeus has close similarities with that of Ae. aegypti. The time of entrapment was early dusk and Service (1971), using suction traps, found unfed females active only in the evening, between 1800-2100h (sunset during his trapping period was from 1902h to 2019h; and the daylength was from 23h20m to 15h20m). There was a very sharp onset and decline of activity, either side of a rounded peak from 1900-2000h. He also reported the time of man-biting as preceding flight by about one hour.

Figure A8

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