The law of population, as finally expounded by Malthus, conceives that increase depends upon the availability of food or upon the ease, difficulty, or ability of procuring it. The consideration of the action of parasites from this point of view, I believe, is of interest and importance, both from the economic and biological standpoints.

The effects of endosulfan and deltamethrin, chemicals used to control Glossina morsitans Westwood (tsetse fly), were tested against Cyrtobagous salviniae Calder & Sands (Curculionidae), a biological control agent for the floating fern Salvinia molesta. The weevil was very susceptible to deltamethrin and less susceptible to endosulfan. The use of these chemicals for control of G. morsitans in Botswana, where the biological control agent is active, is discussed.

Females of Glossina tachinoides Westwood captured three-hourly in biconical traps deployed from 16.30 to 18.30 h weekly in three peridomestic agroecosystems in southern Nigeria from April 1984 to March 1987, were dissected and classified as nulliparous, pregnant, aborted or parous-but-not-pregnant. In all three tsetse populations, the monthly pregnancy rate ranged from 76 to 94% and the abortion rate from 3 to 8% throughout the year. No seasonal or locational differences or evidence of seasonal increase, reduction or cessation in breeding were demonstrated. A significant difference between years with respect to monthly abortion rate during the wet season was possibly due to changes in vegetation structure which is dependent on crop types. It is concluded that the low population density and pattern of seasonal fluctuation in apparent density of G. tachinoides in these peridomestic agroecosystems are due to causes other than seasonal differences in its breeding rate.

Anastatus sp. (Eupelmidae) is recorded for the first time parasitising a puparium of Glossina palpalis (R.-D.) in West Africa. Hitherto, the only records of Eupelmids parasitising tsetse flies have been of A. viridiceps Wtstn. and Eupelmella tarsata (Wtstn.) from G. morsitans Westw. in eastern and southern Africa. The parasite emerged through a large hole anterior to the polypneustic lobes. Parasitic Eupelmids do not normally utilise tsetse flies as hosts.

Aegerita webberi, Fawcett, is a very interesting parasitic fungus which has been recorded as attacking Aleyrodes citri in Florida, Aleyrodes and Aspidiotus in Ceylon, and an undetermined scale in New Zealand, and of which our knowledge has been recently summarised by Petch.* He notes that on the characters of the seal-brown sterile stromata it appeared probable that the forms from the three localities represented three species, but the sporodochia are identical in all, and they must therefore all be referred to A. webberi.

Male and female. Head mainly clothed with black flat scales, with a narrow white border to the eyes broadening laterally, sometimes a central white patch; some upright forked black scales behind. Proboscis black, as long as the front femora in the female, a little shorter in the male. Palpi black; exceeding the proboscis by the length of the apical segment in the male, not quite a quarter as long as the proboscis in the female. Antennae dark brown, pale-banded in the male; the border of the cup of the torus thickly clothed with small flat white scales, especially on the inner side.

Methods that have been used to confine insects to the test surface during exposure to insecticidal deposits are briefly reviewed, and their limitations are discussed. Some unsuccessful preliminary experiments on alternative methods are mentioned.

A temperature-preference method of inducing house-flies, Musca domestica L., to remain on a treated surface is described, and the apparatus is illustrated. The treated surface forms the floor of a chamber; it is maintained at a higher temperature than the walls and lid. The flies are introduced by means of a plunger device.

♀ Integument black, densely squamose dorsally; the head brown, but pale round the eyes and beneath; the prothorax brown (with a slight coppery reflection) and with an ill-defined broad sinuate pale stripe on each side, adjoined externally at the base by a very indefinite blackish patch, and another very vague pale stripe on the extreme dorsal margin, the pleurae with thinner scaling, which is blackish on the upper half and grey below; the elytra brown, usually more or less heavily mottled with black and grey, but interval 1 always brown with a strong coppery reflection, the extreme base of intervals 1 and 4 blackish, that of intervals 2 and 3 and 6 and 7 grey, interval 3 with a conspicuous small black-ringed whitish spot near the top of the declivity, interval 7 mainly grey, and the lateral area below it thinly clothed with black scales and scattered grey ones; the lower surface rather more thinly covered than the dorsum with grey scales having a coppery reflection.

The first species to be dealt with was received from M. Prosper Bovien, of the Statens Plantepatologiske, Forsøg, Lyngby, in October 1927. It was reared from larvae and pupae found abundantly among seed of radish (Raphanus sativum) that had been in storage for months, and it was thought that the larvae were preying on the mites (Aleurobius, etc.) which attack the seed. In a later letter it was stated that some years previously the midges were observed emerging in January from seed in which there were no Aleurobius but numerous Cheyletus. The midge occurs at irregular intervals in seed from Denmark, as well as in seed from Germany.

Blow-flies and house-flies (grouped in the Dipterous family MUSCIDAE in the older sense, including CALLIPHORIDAE) are outstandingly abundant throughout New Zealand. The influence of these insects upon the health of man and domestic animals is well known. Though this work deals with the MUSCIDAE as a whole under local conditions, its main object is to record investigations upon the blow-flies with special reference to the depredations of their maggots upon New Zealand sheep.

Characters are given whereby the gall midges attacking St. John's Wort (Hypericum), a noxious weed, may be distinguished.

Four species, Dasyneura hyperici (Bremi), D. serotina (Winnertz), Macrolabis marteli Kieffer and Zeuxidiplosis giardi (Kieffer), inhabit leaf galls in Europe.

One species, Dasyneura toweri Felt, inhabits the flowers in the U.S.A. Three species, Contarinia hyperici, sp. n., Clinodiplosis hyperici, sp. n. and Lestodiplosis (Coprodiplosis) sp., live in the unopened flowers in Europe.

Two species, Lasioptera virginica Felt and Cecidomyia ? triadenii Beutenmüller, are recorded as attacking the stems in the U.S.A. The latter is a name given merely to a gall.

Four species, Geocrypta braueri (Handlirsch), G. hypericina (Tavares) (perhaps a synonym of G. braueri), Trisopsis hyperici Tavares and Lestodiplosis (Coprodiplosis) hyperici (Tavares), live in underground galls in Europe.

Descriptions of Contarinia hyperici, sp. n. and Clinodiplosis hyperici, sp. n. are given.

Dr. W. Thalenhorst, of the Niedersächsische Forstliche Versuchsanstalt, Göttingen, Germany, sent me some time ago specimens of what he took to be an abnormally dark form of Pachynematus montanus (Zaddach). These had been reared in 1952 from larvae, not at the time distinguished from the larvae of that species and found feeding with them on spruce (Picea abies) in the Harz Mountains in the previous year. Unfortunately the female was smashed in the post and I did not like to describe a new species that would have to be based on only a few males, though I was not able to identify them with any known species. In 1955, however, he reared another female of the same species and from this he tried to obtain eggs but without any success. This female I now have before me. No further specimens have been found.

Two of the weevils referred to by Mr. Wolcott in the foregoing paper as feeding on Coccoloba uvifera are new to science, and descriptions of them are therefore appended.

To lure tourists to the West Indies, the makers of travel literature are most apt to use for illustrations more or less accurate drawings of the coconut palm, as being the most easily recognisable and distinctive tree of these islands. Not so well-known, but quite as characteristic of their sandy beaches, and probably even more abundant, is the sea-grape with its stiff, erect shoots, its large, stiff, rounded leaves, and the gnarled and wind-distorted trunks of the older trees.

There are certain frequently observed and rather mysterious phenomena associated with the bionomics of the better known species of Glossina; such, for example, as the local disparity between the sexes and the apparently arbitrary distribution of the fly. It is difficult, if not impossible, to explain these, or at least no explanation has yet been put forward which is wholly in agreement with all that has been recorded of the subject. It appears necessary in consequence to consider some part of the generally accepted bionomic history of these liies as being based on insufficient evidence.

♀.—Nigra; thorace rufo-ferrugineo; segmentis dorsalibus primo secundoque apice bruneotestaceis, albo-fimbriatis; tertio etiam albo-fimbriato.