The three species of the genus Mus mentioned above follow in the wake of civilised man and may be looked upon as more or less domestic animals. Moreover, when they appear in any new locality, they seem to possess the power of eliminating the previously established native species of rats and mice, and they thus obtain for themselves a wider field and the opportunity for a rapid permanent increase in number of individuals. Of the three, Mus rattus alone habitually infests ships, but by accidental transference in vessels from port to port all three have become distributed throughout the world. Australia is especially rich in peculiar local species of rats, abundantly distinct from, but to some extent resembling, Mus rattus. This circumstance renders it not improbable that on occasion animals from Australia may have been incorrectly identified with that cosmopolitan species.

Notwithstanding the work which has been conducted during the last few years on blood-sucking flies, and particularly on those which occur in Tropical Africa, owing to their connection, whether proved or merely suspected, with the spread of various diseases of man and animals, nothing has hitherto been published on the life-history of any African species of the large family Tabanidæ, except in the case of Tabanus biguttatus, Wied.* It is hoped, therefore, that the following notes on the bionomics of two of the more common Tabanids, though incomplete, may nevertheless be of some interest.

Mites or Acari belong to the class Arachnoidea, which also contains the Scorpions, the Spiders, the minute False-Scorpions, the long-legged Field Spiders and some other curious eight-legged creatures. They are at present considered as a degenerating branch of the Arachnoid trunk. Their larvse are six-legged, their nymphs eight-legged, but deprived of genital apertures.

Apart from the Ticks (Ixodoidea), mites have been generally very much neglected by collectors and systematists alike; but seeing that they comprise a considerable number of species of undoubted economic importance, it has seemed desirable to call attention to them by this brief account of some of the more striking forms. A fuller investigation of their habits and lifehistories, especially as regards tropical species, is certain to yield much information that is likely to be of both practical value and scientific interest.

In a sub-tropical city like Cairo it is most important that, so far as possible, the main streets be protected from the direct rays of a powerful sun by numerous and healthy shade-giving trees. For this purpose, the Lebbek (Albizzia lebbek) has been very extensively employed in Cairo, where it affords a welcome shade, as well as adding very considerably to the appearance of the streets. Until the summer of 1909, these trees have, on the whole, filled their parts quite satisfactorily. They had only one serious insect enemy to contend against, in the form of a longicorn beetle—Xystrocera globosa, Oliv. Hitherto this “borer” has been considered by far the most important pest of the lebbek, since its attacks, although comparatively slow in their effects on the life of the tree, are yet sure, and when extended over a period of years have caused no little mortality amongst the shade-trees of this city. During the past year the importance of this beetle has been, so far as Cairo is concerned, somewhat eclipsed by the depredations of a comparatively new pest—a mealy bug. This insect proves to be new to science, and is described for the first time in the appendix to this paper under the name of Dactylopius pertiiciosus, sp. n.

Ovisac of female (see fig. 2, p. 124). White, or rarely pale buff. Usually more or less reniform, rarely quite globular or more or less hemispherical; surfacewith well-marked transverse, flutings and sometimes also with faint longitudinal striæ. The waxen plates and mealy secretion of the female are often visible on the exterior, more especially so in the earlier stages of the formation of the ovisac. When quite intact it has a closely felted appearance, but on the least disturbance the material is capable of stretching out into long, viscous, elastic threads interwoven with a granular or mealy secretion, which latter disperses in the form of a little cloud of white smoke.

Length 3–5 mm.; rarely attaining a length of 7 mm.

The scale [scale here means both the insects and their ovisacs—F. C. W.] contains a small amount of wax which can be separated by solution in boiling alcohol, or better, petrol. From solution in the latter it yields, after recrystallization, a considerable proportion of a hard wax melting at 83°·5 and having a density of 0·970 at 15° C. This is in all probability Cerylcerotate. There is present a mixture of waxes of lower and indefinite meltingpoint.

Much attention has recently been devoted to the habits of Glossina palpalis, but G. fusca, which I have had the opportunity of observing and collecting in several localities in Nyasaland, has received little notice; the latter has long been known to be most active in the evening, but further points in its habits have come to my notice, and they appear to be worth recording.