Head continuous with the rostrum, not constricted behind the eyes, which are moderately convex, the forehead as broad as the base of the rostrum. Rostrum narrowing from the base to the antennae ; mandibles squamose, mentum bare. Antennae with the scape exceeding the hind margin of the eye, the distal joints of the funicle elongate, joint 2 longer than 1. Prothorax with the base depressed, at a lower level than the apical margin, sinuate or bisinuate. Elytra obovate, widest behind the middle, with or without shoulders. Legs with only the front femora armed with a small sharp tooth ; front tibiae only finely denticulate and with the dorsal edge curved, hind tibiae with the corbels enclosed and not ascending the dorsal margin ; joint 2 of hind tarsi not transverse ; front coxae nearer to anterior margin of prosternum ; claws free. Sternum with the metasternum not longer than a median coxa. Venter with the intercoxal process about as wide as a hind coxa.

The material here described has been received by the Imperial Institute of Entomology, and I am indebted to Sir Guy Marshall for the opportunity of studying it. The types have been presented to the British Museum (Natural History).

Films of oil which have originally covered the whole of the surface of an area of water frequently break up and leave the oil only in patches, and the rest of the surface uncovered. An investigation has revealed that this may be the result of either or both of two circumstances.

It has been shown that instability may result from :—

I. Certain relationships between the volatility of the aromatic and aliphatic hydrocarbons composing the oil mixture.

II. The presence of certain polar substances dissolved in the oil.

I. The volatility relationships which determine the stability or instability are as follows :—

(a) If the aromatic hydrocarbons are more volatile than the aliphatic, a tendency exists for the oil to become concentrated into one central thick lens with the rest of the surface uncovered by oil.

(b) If the whole of the aromatics are more volatile than the whole of the aliphatics, this action is very rapid and occurs whatever the proportion of the mixture.

(c) If the difference in the volatility is only small, the phenomenon is only observed when the proportion of aromatics to aliphatics is very near to unity.

(d) If the boiling range of the aromatics overlaps the boiling range of the aliphatics (as occurs when two oils containing both types of constituents are mixed), the phenomenon is much less clearly defined.

(e) Olefinic oils, e.g., oils obtained by cracking, behave like aliphatic oils in so far as this behaviour is concerned.

It is believed that these changes would not occur if the oil was extremely pure, since lenses are only stable if subject to lateral pressure from an invisible film of contaminating material.

II.—The effect of polar materials can be summarised:—

(a) Solutions of certain organic substances in oil tend to make unstable films on the surface of water; rupture of such a film (by wind or other agitation) allows a unimolecular film of the added substance to spread at the air-water interface. This forces back the oil film. The greater the agitation the less the area of surface eventually covered by oil. In this class of substances are fats, fatty acids, naphthenic acid (a natural constituent of petroleum), some sulphonic acids and cholesterol.

(b) Certain other substances act in a contrary manner. They do not promote instability but actually counteract and, if present in sufficient proportion, overcome the instability produced by the first type of substance. The substances falling in this group are all at present of unknown composition, but include “ cracked spirit gum ” (a material derived by polymerisation of olefinic hydrocarbons), certain resins, and some substance present in petroleum and remaining in the residue after distillation. The last of these acts as a natural “ stabiliser ” and masks the instability phenomenon to some extent in commercial oils. It is found in largest quantity in the undistilled residue of aromatic concentrates.

(c) The quantitative relationship between the “ stabiliser ” and the substances promoting instability is not linear. Successive increments of “ stabiliser ” equalise larger and larger amounts of the other.

(d) Long-chain molecules such as fatty acids are the most difficult to overcome by “ stabiliser.” Naphthenic acid is more easily counteracted, cholesterol still more easily.

The following recommendations can therefore be made as to the desirable composition of anti-malarial mixtures, so far as film stability is concerned :—

1. The oil should contain either a small aromatic content or a very high one ; it should not contain 50 per cent. aromatics unless they are very high-boiling (e.g., of lubricating base fraction).

2. It should consist of a mixture of wide and overlapping cuts of oil.

3. It should not contain fats or fatty acids added as spread-aiders. If spread-aiders are desired, resins should be employed.

This research was financed in its entirety by a grant contributed equally by the Anglo-Iranian Oil Company, the Asiatic Petroleum Company, and the Burmah Oil Company. To the research chemical staffs of these companies I express my thanks for samples of oil and for much technical information and advice. My thanks are also due to Professor P. A. Buxton and Professor N. K. Adam for advice and help.

On the basis of ecological data, breeding experiments, and activity trials, the two species of red spiders (Anychus orientalis, Zacher and Epitetranychus althaeae, Hanst.) found in Palestine are differentiated. The reason for the different distribution of the two species throughout the world is explained. The common red species is found to be a cosmopolitan, the Oriental red spider a subtropical element.

1. Methods for laboratory testing of contact insecticides are reviewed, and some of the disadvantages of these methods are discussed. Reasons are given for preferring an immersion to a spraying method, and the necessity for a supply of “ standardised ” insects is stressed.

2. An improved immersion method for laboratory testing of contact insecticides is described, and the rigid technique necessary is detailed.

3. The effect on the resistance of Ahasverus advena to a derris insecticide of varying the time of immersion, the age of the insects, the temperature and the humidity before, during, and after immersion is illustrated and shows the necessity of controlling all these factors.

4. Results with a standard derris insecticide are given to show the great accuracy that can be obtained by the new method ; that the same result with the same insecticide can be repeated from day to day; and that two workers using the same insecticide have obtained identical results.

5. The reaction to starvation is correlated with variations in age, temperature, and humidity, to show that the starvation death rate is a measure of the insects' powers of resistance to an insecticide.

6. Statistical analysis and discussion of methods of expressing mortality is reserved for a later communication.

Some years ago the Entomological Department of the Swedish Forest Experiment Station was requested to undertake the investigation of the timber-destroying insects in Government buildings in Sweden. In order to obtain a preliminary survey of the amount of damage caused by these pests an illustrated leaflet containing short descriptions of the insects and their galleries was issued and, together with a detailed questionnaire and a circular letter, sent to about 7,000 persons. Altogether 2,148 reports were returned, 990 of which gave detailed information often accompanied by samples of wood for identification.

The fruit-fly damage in the Upper Jordan Valley is limited to the southern belt of Citrus plantations ; further north the fly's activity remains, so far, restricted. There is a permanent fluctuation in the fruit-fly's population density according to ecological conditions, which may change from year to year. This fluctuation is of an irregular character. In years of severe infestation the damage attains 10–15 per cent. of the total crop ; there are seasons, however, when the damage is practically negligible. There is constant danger in the fruit-fly situation, because this fly is able within a short time to increase immensely its population density, if environmental conditions are suitable.

The number of hosts is relatively small in the Jordan Valley ; the Citrus plantations supply sufficient food during 7–8 months, and there is a relatively long summer quiescent period (about 2 months) with an extremely low fruit-fly population ; during the remaining period figs, grapes and other occasional plants serve as hosts.

The fruit-fly is spread chiefly by mechanical agents (wind and transport of infested fruits).

There are 8 generations during the year in the Jordan Valley.

There are two peak infestation periods (October and April-May) and two quiescent periods (winter and late summer).

Fruit-fly control under present cultural conditions should be confined to peak infestation periods only, as unfavourable climatic conditions are responsible for an extremely high mortality of fly later in the winter and in summer.

(a). G. morsitans had been found in banana plantations and it was feared that it might in time establish itself. However, most of these flies had been caught in plantations which were reverting back to natural types of vegetation.

(b). It was shown by the release of marked flies that G. morsitans was repelled by the plantations which were still being cultivated.

(c). Only one G. morsitans was taken by the writer in cultivated plantations. It was demonstrated that flies found in these situations might easily have been transported thither by man or animals.

(d). The temperature in the banana plantations was slightly higher, and the range of the humidity greater, than in the adjacent vegetation. The difference between these physical factors of the two localities is insufficient to account for the flies' preference for natural types of vegetation as opposed to plantations.

Sugar-cane is subject to the attack of a number of insect pests of which the moth borers—Diatraea sticticraspis, Hmps., D. venosata, Walk., Scirpophaga auriflua, Zell. and S. rhodoproctalis Hmps.—are the most serious. During the course of our investigations on Scirpophaga, seven larval parasites, viz., Elasmus zehntneri, Ferr., Stenobracon nicevillei, Bingh., S. deesae, Cam., Iphiaulax famulus, Bingh., Goniozus sp. n., Rhaconotus scirpophagae, Wilkn., and a new species of Rhaconotus have been noted. A paper on “ Studies on Elasmus zehntneri, Ferr., a parasite of the sugar-cane moth borer (Scirpophaga) ” by the authors has already been published. The present paper gives detailed information on the habits and life-history of Stenobracon nicevillei and its efficacy in controlling the pest.

The results of the present investigation can be summarised as follows :—

1. Carbohydrate metabolism in females of all the species studied (except Operophthera brumata) shows a definite dependence on the period of maturation. The greatest quantity of sugar is consumed during the first 4–5 days after emergence. During the period of gonad maturation both the body weight and the oxygen consumption are increased. During the period of oviposition the oxygen consumption is increased once more, but the sugar consumption remains at a low level till death, while the body weight decreases.

2. Sugar (glucose and saccharose) is completely digested when taken in solutions of 5–40 per cent. concentration ; the increase of the body weight during the period of maturation is due to fat synthesis for the formation of egg-yolk. Moths fed on concentrated sugar solutions (of about 20–40 per cent.) show an increased fat content not only before the period of oviposition but even after laying a large quantity of eggs (over 1,000 in Agrotis segetum). In starved moths a nearly complete disappearance of fat was observed at the end of life.

3. The quantity of eggs deposited by starved Agrotis females is greatly reduced ; but such reduction is much less marked in some females of Loxostege sticticalis and almost negligible in Pyrausta nubilalis. Eggs deposited by starved Agrotis females do not complete their embryonic development, the embryos dying before hatching. Agrotis females fed on water only or with 5 per cent. glucose solution produce such “sterile” eggs only to some extent (about 40–50 per cent.). A sufficient food supply (20–40 per cent. solution of glucose) causes a complete absence of “sterile” eggs.

4. The daily readings of the gaseous metabolism 8–10 hours after feeding, for the females fed on glucose, showed an inconsiderable difference as compared with those for starved moths. The respiratory quotient was variable and sometimes very low (0·50–0·60), but on the average somewhat higher than in starved females ; the oxygen consumption showed great variability also and increased in the average only.

5. The readings of the gaseous metabolism directly after feeding showed definite changes. The respiratory quotient was highly increased by a great increase in carbon dioxide production ; it reached an average of 1·50–1·60 and a maximum of 2·09. Oxygen consumption was not considerably increased.

6. Changes in the respiratory quotient show a peculiar metabolic phase after carbohydrate nutrition which is due to fat synthesis. The fat synthesis of carbohydrates results in a decrease in oxygen consumption, because the oxygen liberated by the fat synthesis reaction is used.

7. Carbohydrate metabolism in adult Lepidoptera is highly specialised. The most common type in insects is represented by the combined direct use of carbohydrates and partly by the synthesis of fat ; usually fat synthesis causes no great change in the respiratory quotient. In adult bees the importance of fat synthesis is reduced and the metabolism is restricted to the direct use of carbohydrates ; in the adult Lepidoptera, on the contrary, the direct use of sugar is not developed.

8. The biological importance of the specialisation of carbohydrate metabolism in adult Lepidoptera is evident. Fat is used partly to form the egg-yolk, and therefore carbohydrate nutrition is directly connected with fertility. On the other hand, by using a large quantity of sugar solution (sometimes more than 40 per cent. of the body weight) the live weight could be rapidly reduced owing to fat synthesis.