General Growth.

Generally, females have higher rates of growth than males. The phases, however, do not show appreciable differences in the rate. The pronotum has for increase in length the highest values which decrease throughout the instars (whereas the constants for the other parts remain fairly stable up to the fifth instar).

Dyar's rule was applied for the growth in length of the middle femur and the width of the head, and it was found that the rule holds good for these parts.

Przibram's rule, as modified by Bodenheimer, holds true for the growth in length of the different parts and shows the occurrence of latent cell-divisions varying from one (width of head and of pronotum) to four (length of pronotum). The number of latent cell-divisions keeps fairly constant in both phases.

For wet weight Przibram's principle is inapplicable, owing to the large percentage of differences between the actual and calculated values.

Gregarious males are heavier than solitary males up to the third stadium ; gregarious females are heavier than solitary females up to the third stadium ; fourth, fifth and adult stadia being characterized by higher values in wet weight for solitary females than for gregarious females. Females have higher rates of increase in wet weight than males. No significant differences exist in the rates of increase between gregarious and solitary individuals. In the fifth-adult stadium all the rates decrease except in gregarious females, which show a rise.

Gregarious insects have higher values in dry weight than solitary insects, except solitary females in the adult stadium. The coefficients are higher for females than for males.

The rates of increase reach the highest values in the second-third stadium of gregarious insects and solitary females, whereas solitary males have their highest value in the fourth-fifth stadium.

With the exception of solitary females, all the rates of growth in dry weight decline in the fifth-adult stadium.

The rates of growth of the hind legs obtained from the cube-roots of their wet weights are compared with the rates of linear growth of the hind femora. Their variation throughout the instars seems to be in opposite directions. Therefore it is suggested that the rates of growth in wet weight of the hind legs and the rates of growth in length of the respective hind femora are independent of each other.

Growth of the parts.

The application of the exponential allometry formula y=bxα to the data on dimensions of the parts of Locusta shows the existence of negative, positive and almost isometric growth.

The pronotum has the highest value for the growth in length relatively to the growth in length of the middle femur ; the lowest value pertains to the growth in width of the head.

Males have higher values than females ; phase gregaria exhibits higher growth-ratios than phase solitaria.

With the exception of the hind femur the growth-ratios decline throughout the instars. The greatest decline pertains to the growth in length of the pronotum.

A growth-gradient exists in Locusta with the highest value in the pronotum. The middle femur divides the growth-gradient into two parts : an anterior part with values decreasing with the growth of the insect, and a posterior part whose values increase with its growth.

Effects of the amputation of the hind tibiae on crowded locusts.

The effects obtained by mutilating both hind tibiae of three hundred first instar hoppers of Locusta migratoria migratorioides and placing them in a crowded condition are compared with the effects obtained by crowding a batch of the same number of first instar unoperated insects.

The insects with their hind tibiae cut off did not develop as far as those of the control batch ; the differences in dimensions are greater for the hind femur than for the other parts of the body.

In the experimental batch the hind femur, as a consequence of its useless condition, became extremely short as compared with the elytra, bringing the ratio E/F to a high value (over 1·950), thus leading to a false interpretation.

The occurrence of the black-orange coloration in both batches suggested that both developed towards phase gregaria. This coloration was stronger and more uniform in the control batch than it was in the experimental batch. Thus the control animals developed into a better gregarious type.

1. The moth—Cydia nigricana—whose larvae bore into the pods of developing peas and render most of the contained seeds unfit for human consumption is considered by some authorities to be one of the principal insect pests of agriculture in Canada. It is particularly destructive in the Maritime Provinces and British Columbia, while in Ontario it increased to such proportions that the farmers of that province had to give up growing mid-season peas altogether.

2. This state of affairs is attributed to the fact that the pea moth was accidentally introduced from Europe in 1893 without the insect parasites which attack and check it in its native home. At any rate no parasites have emerged from the representative collections of pea moth material made by the Canadian entomologists in the affected areas, while three species with a combined parasitism of up to 60 per cent. have been reared by the writer from cocoons of the moth in England. Furthermore, in Canada, where parasites of this particular pest are absent, 10–50 per cent. of the pea crop and sometimes as much as 75 per cent. or more, is said to be destroyed annually by the moth larvae, whereas in England, where they are present, the attack is usually comparatively slight.

3. The paper opens with a general account of the biology of the pea moth including systematic descriptions of the adult and developmental stages, and notes on the host-plants and distribution of the insect.

Die Wanderheuschrecke (Locusta migratoria, L.), in früheren Jahren in Rumänian einst eine der gefürchtetsten Plagen, ist heute meist auf das Donaudelta beschränkt ; sehr selten sind Jahre, wo der Massenwechsel in dem Masse sich gestaltet, dass sie das Gebiet auf weitere Strecken verlässt.

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.

The Encyrtidae reported upon in this paper are mostly Coccid-inhabiting species, received by the Imperial Institute of Entomology from various collectors in Africa and forwarded by Dr. C. Ferrière for identification. The species of Microterys, Metaphycus, and Anicetus will be reported upon in separate papers at a later date, All holotypes and allotypes are deposited in the British Museum; paratypes will be deposited in the United States National Museum.

During the latter half of 1936 a search was undertaken for predators and parasites that might be of use against certain Coccidae which are causing considerable damage to the coconut crop in Seychelles.

During recent years in Sweden much time and work has been devoted to the devising of accurate and withal time-saving methods of estimating the number of bark-beetles breeding in a trunk as well as the total number of bark-beetles per hectare in a given instance. The results achieved by the methods finally adopted seem to us so satisfactory that we venture to think that the methods in question may be used to advantage even in other countries, when similar problems arise.

(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.

Protostrophus dianthi, sp. n.

♀. Black, with dense grey and pale brown scaling ; head brown with a grey stripe adjoining the eyes ; prothorax with a broad indefinite median brown stripe, the lateral areas grey with brown spots which sometimes form two narrow irregular stripes, the pleurae brown above and grey below ; elytra mottled with pale brown and grey, intervals 2, 5 and 6 usually with dark brown patches, the suture pale fulvous.

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.

The Nigerian Agricultural Department is endeavouring to find cattle with a sufficiently high degree of natural resistance to trypanosomiasis to enable them to be utilised for mixed farming in the Ilorin Province and elsewhere in the Middle Belt of Nigeria. In April 1935, a herd of West African Shorthorn cattle was obtained from the Gold Coast and these and other animals, purchased in Nigeria, were established at a central stock farm at Ilorin.