The object of the present work is to study the histological picture of the intestinal tube of insects when subjected to the action of insecticides, in order to discover the mechanism of the action of poisons on insects.

Such knowledge as we have of the family Lacciferidae is very largely embodied in an excellent monograph published in 1923 and 1925 by J. C. Chamberlin (Bull. Ent. Res. 14, pp. 147–212 and 16, pp. 31–41). The comparatively speaking limited geographical distribution of the various generic groups is well brought out in this monograph. Thus, for instance, the genera Tachardiella and Austrotachardiella are apparently confined to North and South America, Metatachardia to Ceylon, Austrotachardia to Australia, Tachardia to India and the Far East. Chamberlin further states (p. 149) “ in general it may be said that the species of this group are tropical or sub-tropical, apparently reaching their greatest abundance in regions of limited rainfall.” How far this comparatively limited and well-defined zonal distribution of the various genera will hold good as further material is collected will prove of the greatest interest.

1. When studying the effect of intermittent starvation upon the length of development of the larval phase it is necessary to carry out experiments with each stage separately. Ignoring this factor and carrying out experiments on the larval phase as a whole results in serious errors.

2. The shorter the periods of feeding and consequently the longer starvation periods during each 24 hours the stronger their effect upon the length of development of each stage.

3. More than 50 per cent. of larvae fed only for 2 hours a day and starved for 22 hours accomplish their complete metamorphosis and produce moths that are fully capable of living.

4. The length of development of each stage depends upon the feeding regime during the previous stage. Using the same starving regime, development of the last stage is the longer the earlier the stage at which larvae were subjected to this regime.

5. At different stages of development larvae react differently to the same starvation regime. Thus starving for 12 hours a day increases the duration of the development of the 3rd stage by 104 per cent. ; that of the 4th stage does not increase at all, while the development of the 5th stage increases only by 31 per cent.

6. Nature of food greatly influences the length of development under conditions of intermittent starvation. Starving for 8 hours a day when feeding larvae on wormwood results in greater increase of development than starving for 12 hours a day when feeding on goose-foot.

7. All factors influencing the development of the larval phase result in decreasing the weight of the pupae. Decrease in weight of pupae is the greater the longer the starvation periods and the earlier larvae were subjected to starvation effect. Nature of food also highly affects the weight of pupae.

8. Intensity of feeding during feeding periods of starving larvae does not decrease as compared to control. With very strongly starving larvae intensiveness of feeding even increases.

9. There is no direct proportion between the quantity of excrement passed, that is amount of food consumed and the weight of pupae. The longer the development, the more there are feeding periods and consequently the more excrement passed. Owing to the lengthening of development the most part of substances consumed are spent on vegetative functions ; therefore there cannot exist direct connection between the number of excrement passed and the weight of pupae.

Ten years have now elapsed since the first dusting operations by aeroplanes were carried out against forest insects in Germany. It is therefore a tempting task to try to review the development of this modern method of fighting forest insects and to formulate, at least tentatively, some fundamental conceptions regarding the specific conditions which must be fulfilled before this method is resorted to.

1. The report covers a period of 3½ years actually spent in the field.

2. During this time 19 major pests have been studied, with special reference to their natural enemies and other limiting factors. The pests of sugar-cane have, however, received by far the most attention, partly because this is the most important crop throughout the region as a whole, and partly because the industry has made substantial financial contributions.

3. Advice has been given, on request, to local Governments, planters' organisations and individual planters, and schemes have been drawn up for intensive local research on cane-borers, on froghopper and on mongoose. The researches of the two investigators of the cane-borer (Diatraea spp.), under grants from the Colonial Development Fund, have been supervised so far as their technical aspect is concerned.

4. For the control of the small moth-borer (Diatraea) the most important pest of sugar-cane as a whole, the Cuba fly (Lixophaga) has been introduced (in collaboration with Mr. Box) into the Leeward and Windward Islands, and the Amazon fly (Metagonistylum) into British Guiana (in collaboration with Mr. Cleare). Both these very promising parasites, the second of which was discovered during the course of the investigation, are now widely established.

5. A specific parasite is now needed for Diatraea canella in British Guiana and D. impersonatella in Trinidad. It is possible that experiments now in progress (in collaboration with Mr. Pickles and Mr. Cleare respectively) that Paratheresia will serve for the first and Metagonistylum for the second, but a highly specific parasite for D. canella remains greatly desirable.

The air-pump which is described in the present paper was designed in order to replace the rubber double-bellows type of inflator supplied with apparatus for use in the preservation of larvae. In the tropics, the life of articles manufactured from rubber is a comparatively short one, since rubber perishes if frequently handled, or even if stored, in spite of being packed in French chalk. The only rubber article necessary for use with this pump is tubing, which is easily replaceable. In Malaya, it has been found that the double-bellows type of inflator is unsatisfactory, owing to its rapid deterioration.

During a recent study of some insect and other pests of the cardamom plant in two or three tracts in South India, a new species of thrips was noted doing some appreciable damage to cardamom capsules on an estate in the Anamalai Hills, and this is described below.

This paper is based on material submitted for identification by the Imperial Institute of Entomology and received from Mr. G. H. Corbett, Government Entomologist of the Federated Malay States.

1. Apanteles sesamiae, Cam., is the only parasite of Busseola fusca, Fuller, which is of importance in the Eastern Transvaal.

2. The adult is described, and the morphology of the last stage larva of the parasite is discussed in detail.

3. The biology and bionomics of the species are dealt with, and the effect of parasitism on the host is described.

4. The extent of natural parasitism and the rapidity of increase in the field shows that A. sesamiae is an effective parasite of the Maize Stalk-borer in South Africa.

5. The results of cold storage experiments are given and the methods of shipping parasite material are described. It was found impracticable to ship cocoons, but successful consignments of parasitised borer larvae were sent to Canada.

So far as the writers are aware, there is very little on record regarding insect pests of cardamom, especially of those affecting the growing crop, in India. This is chiefly due to the fact that this crop is grown only in some select forest areas, and we get very few opportunities of studying its diseases. The only insects so far recorded as casual pests of cardamom appear to be (1) the shoot-borer caterpillar (Dichocrocis punctiferalis, Guen.) recorded by Macmillan in 1925 ; this is a well-known pest of castor, turmeric and ginger in the plains. (2) A capsule-boring Scolytid beetle, a minute dark brown insect boring in the capsules like the rice weevil; it is not quite clear from the available information in the records from Coorg whether this was noted as a pest of the growing crop or only in the stored dry capsules. (3) The cardamom borer, Lampides elpis, Godt., the pinkish caterpillar of a small blue Lycaenid butterfly which has been noted to attack the flowers and pods to a certain extent but not seriously. (4) A swarming caterpillar (Eupterote sp.) which was once noted as causing substantial defoliation of the crop. (5) A white delicate lace-wing bug (Stephanitis typicus, Dist.), a minor pest also found on turmeric and ginger. A few others, like Ischnodemus vochus, Tol. (a bug) and Hilarographa caminodes, Meyr. (a root-boring caterpillar), have also been noted off and on ; but none of them has ever attained the status of a serious pest.

In 1927 and 1931 the writer published two papers on the food-plants of some Nigerian insects; the present paper contains additional data obtained since 1931. The writer wishes to acknowledge his indebtedness to the Imperial Institute of Entomology and the specialists of the Department of Entomology in the British Museum for identifying the insects mentioned and to Messrs J. West and O. J. Voelcker for supplying him with many of the Lepidopterous larvae.

1. All the species of Siberian grasshoppers that have been studied in sufficient detail consist of a series of races exhibiting parallel coloration, structure and behaviour characters.

2. Every race of Chorthippus albomarginatus, Zett., Aeropus sibiricus, L., and of other species, has in its hopper and adult stage a series of colour forms analogous in their characters to the phases solitaria, transiens and gregaria of swarming locusts.

3. These colour forms are very unstable and undergo changes during the individual life due to the conditions of breeding.

4. Breeding in crowded conditions results in the predominance of dark-coloured forms, with black and sometimes with orange spots. Breeding in isolation, on the contrary, results in light forms of various colours.

5. No complete transformation of all the individuals in a population is observed in Siberian grasshoppers, and the intermediate forms represent a considerable portion of every population.

6. These colour forms, which can be considered as phases, differ also in their structural characters. Phase gregaria is larger and more long-winged than phase solitaria.

7. The phases differ further in their behaviour, ph. gregaria being more mobile and inclined to migrations, than ph. solitaria.

8. Every species and every race which have been studied exhibit a potential ability to produce phases, but this ability is not equal in all species and races. Those species and races which, owing to their habits and to the conditions of their habitats, can multiply in masses in restricted areas are more inclined to phase variability.

1. The effects of humidity upon the rate of development of the egg, larva and pupa of Heliothrips haemorrhoidalis, Bché., is quite negligible.

2. The rate of development and reproduction primarily depends upon the temperature.

3. The larva and adult are more resistant to the ill effects of combined temperature and relative humidity than are the egg and pupa.

4. Humidity of above 87 per cent. is the safe zone for the development of the pupa.

5. A temperature-activity scale for Heliothrips is given.

6. The plant tissue wherein the egg is laid may have a detrimental effect upon the egg under certain conditions.

7. The effects of the particular climatic conditions of Palestine on the seasonal abundance of the insect are described.

An illustrated description is given of the construction details of a stable trap in Jamaica to catch Anopheline mosquitos. This trap is of knock-down type, which is more portable than many traps used for the same purpose.

Mosquito “ catches ” from stable traps are a means of obtaining information for planning anti-Anopheline work in a new area. These “ catches ” can be carried out with regularity and can give data to indicate the need of strengthening control measures to deal with the seasonal emergence of different mosquitos in specified zones.

The area in which the Health Officer of Kingston requires information about the prevalence of Anophelines is so extensive that nearly fifty regular mosquito catching stations should be visited at least twice a month. In order to obtain the needed data with the present staff, the writer recommends the simultaneous use of six portable stable traps.

In 1930 the available information regarding gall midges as enemies of the Coccidae was summarised in a paper published in the Bull. Ent. Res. (21, 1930, pp. 319–329). Since that time there have been several additions to our knowledge concerning such midges. Some of this knowledge was cited as an addendum in a later paper on gall midges as enemies of mites (Bull. Ent. Res. 24, 1933, pp. 215–228). It is proposed in this paper to bring this subject up to date by referring to published work and by describing some new forms that have been received for identification in the immediate past.

The selection of examples where the biological control method has been successful depends somewhat upon the individual viewpoint. A casual perusal of the literature would lead one to believe that predators and parasites had been unusually successful against many pests. In a recent communication from H. S. Smith it was stated : “ If you go over the old literature on this subject in California, you will find that the black scale problem was solved by the introduction of Rhizobius in 1890. It was solved again in 1900 by the introduction of Scutellista. But we still spend in excess of a million dollars a year in southern California on spraying and fumigation for this pest. The same was true in Hawaii. For many years it was stated that one of the greatest examples of successful biological control was that of the sugar-cane leafhopper by the egg parasites, Paranagrus and Ootetrastichus. Later Cyrtorhinus was introduced with success, and it was admitted that control by the two egg parasites was not satisfactory. No doubt all these introductions were valuable and represent different degrees of control, each succeeding introduction resulting in a greater degree of control than previously existed. The difficulty lies in the absence of a satisfactory criterion by which to measure and record the relative effects of the introductions.” A critical analysis of the data submitted to support the contentions for the early examples mentioned above is far from convincing. However, it should be recalled that the standards for measuring the success of biological control have undergone considerable change during the intervening period.

The mouth-parts of male mosquitos are referred to in many text-books, but the descriptions given by various authors differ to a quite remarkable extent. This fact is particularly noticeable in regard to the maxillae and the mandibles. It is usually (and correctly) pointed out that maxillae are present in the male proboscis ; but the statements made by different observers concerning the length of these organs are extremely discordant. As to whether the male proboscis contains mandibles in addition to maxillae, opinions are sharply divided, the majority of writers asserting (as we shall see, incorrectly) that such is not the case.

The following addition to the Coccidae consists of eleven new species which are assigned to the Pseudococcine genera Rhizoecus and Ripersia. A number of indigenous species of root-infesting mealybugs have been implicated with fungoid associates in the causation of certain root diseases of important economic plants in East Africa and the systematic description of hypogeic Coccidae in that area cannot fail to have economic significance.

The paper deals with the control of insects by hand-collection. An experimental study of the method as used against Antestia on coffee in Kenya is described. The rate of increase of the yield of insects collected falls off in a definite and measurable manner as the time spent on the work increases. The formula for the curve fitting the results is P = 100(1 − (V.e.)−t) where “ P ” is the percentage collected of the total Antestia present, “ t ” is the time spent collecting, and “ V ” is a coefficient which has different values according to the conditions prevailing. In practice one careful experimental picking provides data for the calculation of the formula which may be used to determine the cost of hand-picking any percentage.

The results show that in theory 100 per cent. of the insects can never be obtained by hand-picking, and that in practice the cost of picking an adequate percentage is almost invariably prohibitive.

It is probable that the experimental results obtained will prove valid in other cases of hand-picking. Much of the expenditure on this method is unproductive.

Details of a thorough long-continued attempt to control Antestia on thirty-five acres of coffee by hand-picking are given. The attempt proved unsuccessful, and it is suggested that it may actually have been responsible for the maintenance of the severe attack.

The kind co-operation and assistance of a number of coffee planters are acknowledged. Except for the first experiments in 1933 Mr. H. Naismith Jones assisted me throughout, and the investigation owes a great deal to his careful supervision of much of the field work.