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VI.-Hosts and Host Preferences of Glossina palpalis :-
(a) General comments on-
(1) Methods of studying hosts and host preferences;
(2) Attractive and repulsive hosts;
(3) Most favoured hosts.
Table XVII. Summary of observations on hosts and host preferences,
showing methods of study and conclusions reached.
(b) The habits and habitat of the hosts, or possible hosts, of Glossina palpalis in the region of Victoria Nyanza in Uganda: (1) Crocodile; (2) Varanus; (8) Tor- toise; (4) Serpents; (5) Small Lizard; (6) Situtunga; (7) Hippopotamus; (8) Bush Buck; (9) Bush Pig; (10) Water Buck; (11) Zebra; (12) Wart Hog; (13) Reed Buck; (14) Duiker; (15) Buffalo; (16) Leopard; (17) Monkey; (18) small mammals; (19) birds; (20) domestic animals; (21) Man.
of fly
(c) Experiments with animals under constraint to determine host preferences
(1) Comparison between Goat, Pig, Varanus, and Man.
Table XVIII. Showing strong preference of fly for Varanus over Goat, Pig,
and Man.
(2) Comparison between Goat, Varanus, and Crocodile.
Table XIX-Showing strong preference of fly for Varanus and Crocodile
over Goat.
(3) Comparison between Ox, Sheep, and Varanus.
Table XX.-Showing well marked preference of fly for Varanus over Ox,
for individual Öxen over others, and for Oxen over Sheep. Table XXI. Showing correlation between presence of Tabanus and relative
immunity of Ox, but not of Varanus, to attacks by Glossina.
(4) Comparison between Varanus and Man.
(d) Observations upon animals in natural environment to determine host preferences of Glossina palpalis (1) Varanus; (2) Crocodile; (3) Situtunga; (4) Tortoise; (5) Monkeys; (6) Otter: (7) Mongoose; (8) domestic animals; (9) Man. (e) Observations upon flies accompanying game animals shot, in fly belt, as indicative of host preferences, including Crocodile, Situtunga, Bush Pig, Bush Buck, Water Buck, Domestic Pig (run wild), Hippopotamus.
Longshore range and density of fly as affected by food-supply.
Effect of Crocodile on longshore range.
Graph V-Showing specific case in which the presence of fly is explained
by the presence of Crocodile.
VII. The Breeding Grounds of Glossina palpalis :-
(a) Breeding-grounds in sand and gravel beaches.
Table XXII. Showing concentration of pupae in attractive breeding-places. Table XXIII.-Showing variations in proportion of late and early stages of pups in attractive breeding-grounds, possibly indicative of variable rate of reproduction.
Table XXIV-Showing proportions of healthy puparia to empty shells, in
attractive breeding-grounds.
Table XXV. Showing high degree of protection afforded by good breeding
places against predatory destructors.
Note on correlation between choice of breeding-places and habitat of favoured
hoots.
(b) Breeding-grounds in vegetable débris.
Table XXVI.-Showing find of puparia and shells in breeding-grounds in vegetable débris, indicating-when compared with Table XXII.—that these are less attractive than breeding-grounds in sand and gravel. (c) Observations on all breeding-grounds found at a distance from lake shore. (d) The fly beaches.
to
Table XXVII. Showing the conditions of life along the "fly beaches
be measurably superior for tsetse over conditions of life elsewhere.
(The most extensive breeding- (e) Breeding-grounds in old beach lines. grounds were found along a line representing the high-water mark of 1906, several feet above, and a variable distance inland from the foreshore of 1913-14 and 1915.) (A) Correlation between extent and character of breeding-ground in sand and gravel and degree of infestation of small islands.
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Table XXVIII.-Showing correlation in some cases and complete absence of
it in others.
(g) Correlation between extent and character of breeding-grounds in sand and gravel in regions where food, shelter, and enemies can be eliminated as factors controlling density.
Graph VI-Fly survey of Bugaba Island: showing complete correlation between density of fly and location and extent of breeding-grounds. (h) Conclusions.-The factor of insularity. (Arbitrary restrictions of the normal dispersive movements of the fly, such as occurs on very small islands, may result in small and unattractive breeding-places being much more frequented by flies which cannot get away from them or find any others more attractive-than will ever be found on the mainland or on large islands, where the flies are free to disperse. Conclusions must be based on such data as are presented in Graph VI. rather than on such as presented in Table XXVIII.)
VIII.—“ Shelter" of Glossina palpalis :-
(a) Correlation between character of shelter and degree of infestation of small· islands.
Table XXIX.-Showing correlation in some cases and lack of it in others. Diagram II., with notes, showing the need of "massive" shelter, and insuf-
ficiency of "light" shelter, such as is most attractive to active flies. (b) Correlation between types of shelter ("massive" and "light") and density of fly as disclosed by fly survey of large islands and mainland.
Graph VII-Illustrating need of massive shelter, as shown by reduced
density of fly in Lutoboka Bay. Table XXX-Results of fly survey of southern shore of Buganga Penin- sula, showing slightness of infestation traceable to absence of "massive" shelter.
(c) Occurrence of fly behind papyrus or sudd.
Conclusion: The fly occurs behind fringes of papyrus and sudd sufficiently
narrow to permit landing of crocodiles.
IX.-The Natural Enemies or Inimical Factors in Bionomics of Glossina palpalis:- (a) The hosts of Glossina as destructive factors in its bionomics. (Monkey
is so dangerous a destructor that flies sedulously avoid it; man is also a dangerous
enemy.")
(b) Predatory destructors of adult flies :--
(1) Spiders.
Table XXXI.--Insects found entangled in spiders' webs, showing relatively
large number of Glossina.
Table XXXII-Survey of small islands, showing measurably less density
on islands densely infested by spider, apparently due to this circumstance. Dragonflies.
Bember.
(4) Miscellaneous.
(c) Parasitic and predatory destructors of larvae and pups.
(1) Ants.
(2) Hymenopterous parasites.
(8) Miscellaneous.
Table XXXIII.-Showing variable degree of protection afforded by different
breeding-grounds to pupæ against destructors.
(d) Inanimate destructive factors.
(1) Sun.
(2) Storms.
Graph VIII. Showing effect of distantly passing storms on activity of fly.
(3) Flood.
(4) Fire.
(The presence of (e) Secondary environmental factors detrimental to fly. spider, of dragonfly, or other destructors in sufficient numbers to affect density of fly is always due to some secondary environmental factor, equally as important in the bionomics of the fly as the "enemy" itself.)
(Leopard as a deprivative enemy of Glossina. (When Leopard is absent (on islands) Situtunga increases and fly increases in density and extent of range over what is possible in presence of Leopard.)