This subfamily comprises a large number of genera, which are, as a rule, easily distinguished by the presence or absence of secretionary matter in one form or another. All agree, however, in having the anal ring with a number of hairs and, further, in having the hind margin cleft. The anal ring is covered above by a pair of more or less triangular plates which are usually densely chitinised. The eighteen genera known to be represented in South Africa are tabulated.

The material belonging to this family brought back by the expedition includes representatives of only four species, one of which, however, is apparently new. That three out of the four species obtained should belong to the Aegophagamyia-Bouvierella group is not surprising, in view of the predominance of this group in the Malagasy Subregion.

The effective action of formaldehyde as a fly poison depends on the freedom of the exposed fluid from formic acid, and. to a less extent, from methylamine. That used for fly poisoning should therefore be colourless and free from a fishy odour, and a weak alkali, in slight excess, should be added in dilution to neutralise any acid present and that which will be formed during exposure.

The following new species of Aphids have been sent from Africa; four are from a collection forwarded by Mr. Claude Fuller of the Department of Agriculture of the Union of South Africa (Macrosiphum cissi, Phorodon violae, Capitophorus chrysanthemi and Forda natalensis); one has been sent by Mr. C. C. Gowdey from the British East African Protectorate which has to be placed in a new genus (Cerciaphis).

With the filling up of Gatun and Mira Flores Lakes, water lettuce (Pistia stratiotes, Linné) and water hyacinth (Eichornia crassipes, Solms.) rapidly increased in numbers until large areas became completely covered by them. Masses of these plants would become detached and float about in these lakes. It was found necessary to destroy these “floating islands,” not because they were serious mosquito habitats, but because they interfered with navigation and the operation of the spillways. The water lettuce is the habitat of the very specialised larvae of Mansonia, of which titillans is the commonest member. Knab (1913) and Busck (comments appended to Mr. Knab' paper) refer to the changes in the mosquito fauna brought about by the rapid increase in Pistia. Both Mansonia titillans. Walker, and Aëdomyia squamipennis (Lynch-Arrib.) Theo., have been collected by me in very large numbers since 1912, and to-day Mansonia is the dominant species caught in the army barracks on the west side of the canal. Knab expressed the opinion that perhaps measures would have to be taken to destroy the Pistia habitats; now that we have found Anopheles larvae in them, this prophesy comes closer home.

The following species and varieties have been found in the Malay Archipelago*:—

Myzomyia: ludlowi, rossii, vaga (indefinita), flava, minima, minima var. aconita.

Neomyzomyia: leucosphyra.. punctulata var. tesselata.

Cellia: kochi.

Myzorhynchus: sinensis, sinensis var. vanus and var. separatus, barbiiostris, barbirostris var. pallidus, albotaeniatus, mauritianus, umbrosus, gigas

Nyssorhynchus: fuliginosus, maculatus, schiifEneri, karwari, jamesi, annulipes var. moluccensis.

Stethomyia: aitkenii, aitkenii var. insulae-florum and var. papuae.