250 
Anopheles in Flanders 
22 (20-7 %); 17 (16*1 %) records are doubtful. In 2 cases the number of 
larvae was many thousands. 
(12) On 9 occasions Anopheline larvae were found in polluted water. 
(13) Anopheline larvae were found almost certainly in all waters where 
the visible vegetation was grass or algae or predominantly one of these. 
Association with water-cress was not infrequent. Ponds entirely covered with 
a dense mat of duckweed never gave Anopheline larvae but, at times, such 
pools may have open patches among marginal vegetation and in these patches 
the larvae have been taken. They have also been found in water which showed 
no visible foodstuffs. 
(14) Anopheline larvae were found alone in 65 % of cases, and co-existing 
with Culicine larvae in 24 %, with water hog-lice ( Asellus) in 6-5 % and with 
fresh-water shrimps ( Gammarus) in 1-2 % of cases; they may also co-exist 
with any two or all three of these, and with fresh-water fish of many kinds. 
(15) Water-boatmen ( Notonecta ) have been observed in an aquarium to 
prey upon and suck the juices of Anopheline larvae. 
(16) All waters are suspect. 
(17) It is probable that further summer work would show the number of 
Anopheline waters and the degree of infestation of the districts to be higher 
than the results here cited. 
(18) Anophelines have been found generally distributed all over the area 
and in close proximity to billets. In 4 districts out of 20 examined, none was 
found, but more careful search would probably reveal them. 
(19) The results obtained in the Hazebrouck district are taken as repre¬ 
sentative of the approximate degree of Anopheline infestation to which the 
Second Army area attained. The findings are (1) 14 % (1 in 7) of waters 
examined were Anopheline; (2) there were 5 Anopheline waters per square 
mile; (3) 25 % of Anopheline waters contained numerous larvae and 56 % 
contained few; of the remainder there is insufficient record. 
(20) Generally speaking, and as far as information of the conditions 
obtaining in other regions in the temperate zone permits comparison, the 
degree of Anopheline infestation of the whole area appears to be low; compared 
with sub-tropical regions formerly war zones—Italy, Macedonia, and Palestine 
—it is very low. Two districts, Moulle and Arques, showed waters highly 
infested, both being in the neighbourhood of hospitals. The ditches of the 
Waterlands district showed a low degree of infestation. 
(21) The nature and character of the Anopheline waters render them 
amenable to treatment by dragging of weeds and oiling and, military exi¬ 
gencies permitting, sufficient preventive measures could be instituted to bring 
Anophelines under control. 
(22) Notwithstanding that the area has been densely populated with 
a great variety of malarial troops and that a few cases of “ primary ' malaria 
have occurred, an epidemic of malaria among troops or civilians is unlikely. 
(23) In instituting preventive work under war-conditions cognizance 
