1. The survey of Diatraea spp. in their primitive habitats has been extended to cover the interior Guiana plateau, the Rio Branco, the lower Rio Negro and the lower Amazon.

2. The greatest practical result has been the discovery and introduction into British Guiana of the Amazon fly parasite (Metagonistylum minense) of D. saccharalis.

3. The most interesting ecological result was the finding of several Diatraea spp. as original members of a true savannah association.

4. The twelve species considered are grouped as forest, riparian, savannah and domestic species.

5. The two forest species are D. bellifactella and D. brunnescens.

6. Riparian grass associations are developed over huge areas on the lower Amazon, where they may be divided roughly into three main zones, dominated by Paspalum repens, Echinochloa polystachya and Paspalum fasciculatum, respectively.

7. The chief, and in fact only Diatraea of the first and second zones, is D. saccharalis, which is occasionally abundant.

8. The P. fasciculatum zone is colonised by D. amazonica and D. myersi.

9. The pure savannah species are D. canella, D. impersonatella, D. savannarum and D. cayennella.

10. D. lineolata is practically confined to maize, and no wild host-plants, either naturalised or indigenous, are known.

11. Five species attack cane, namely, saccharalis, busckella, impersonatella, canella and albicrinella, and all except the latter are major pests over considerable areas.

During the last decades, an increasing number of predators were found to use specific prey pheromones as chemical cues. Beyond its ecological relevance, this knowledge has practical applications on insect conservation and pest control. In this study, we present first evidence that two species of the family Dasytidae (Coleoptera) Aplocnemus brevis Rosenhauer and A. raymondi Sainte-Claire Deville use the sex pheromone of the pine bast scale Matsucoccus feytaudi Ducasse (Hemiptera: Matsucoccidae) as kairomone to locate this prey. The feeding habits and biology of Aplocnemus species are practically unknown. In the laboratory, the adults of Aplocnemus sp. accepted M. feytaudi egg masses as food source as well as other diets. Females represented more than 90% of Aplocnemus sp. attracted to the pheromone lures. We believe that females use this olfactory cue to locate suitable places for oviposition and that larvae are the predators of Matsucoccus. This study further demonstrates that the response to the kairomone elicited short prey searching times, about 23% of the individuals appeared less than 12 min after lure exposure, being consistent with the hypothesis of prey specialization. Habitat and geographical distribution predict an ancestral association of A. brevis with M. feytaudi and of A. raymondi with M. pini. Nevertheless, a recent prey shift of A. raymondi to the invasive M. feytaudi in Corsica is in progress.

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.

Heather, Calluna vulgaris (L.) Hull, is a serious invasive weed in the central North Island of New Zealand, especially in Tongariro National Park, a World Heritage Area. Heather beetle, Lochmaea suturalis (Thomson), is a foliage-feeding pest of Calluna in Europe, that was selected as the most promising biological control agent for introduction into New Zealand, because it causes high levels of damage to Calluna in Europe. Host-range tests indicated that L. suturalisposes a negligible threat to native New Zealand plants. Cultivars of Callunagrown as ornamentals are suitable food plants, but are unlikely to be severely affected because L. suturalis requires a damp understorey of moss or litter for successful oviposition and pupation, which is rarely present in gardens. However, mosses and litter occurring under Calluna stands in Tongariro National Park are suitable substrates for eggs and pupae. Lochmaea suturalis released in New Zealand has been freed of parasitoids and a microsporidian disease that attack the beetles in Europe.

The bird cherry ermine moth, Yponomeuta evonymellus L., is considered an obligatory monophagous insect pest that feeds only on native European Prunus padus L. In recent years, however, increased larval feeding on alien P. serotina Ehrh. has been observed. In both species, general defoliation is extensive for shade grown trees, whereas it is high in P. padus, but very low in P. serotina, when trees are grown in full light conditions. The aim of the present study was to identify how the plant host species and light conditions affect the performance of Y. evonymellus. The influence of host species and light condition on their growth and development, characterized by the parameters of pupation, adult eclosion, body mass, potential fecundity, and wing size, was measured in a 2 × 2 experimental design (two light treatments, two hosts). In comparison with high light (HL) conditions, a greater percentage of pupation and a longer period and less dynamic adult emerge was observed under low light (LL) conditions. The effect of host species on these parameters was not significant. In contrast, mass, fecundity and all of the studied wing parameters were higher in larvae that grazed on P. padus than on P. serotina. Similarly the same parameters were also higher on shrubs in HL as compared with those grown under LL conditions. In general, light conditions, rather than plant species, were more often and to a greater extent, responsible for differences in the observed parameters of insect development and potential fecundity.

In common with the rest of southern-central Africa (Uvarov, 1933) the Nyasaland Protectorate was affected late in 1932 by the spread of the sixth generation of the red-winged locust. The course of the invasion, development of subsequent generations, and the damage done have been fully described in the Annual Reports of the Department of Agriculture for the years 1933 to 1934 (Smee, 1934, 1935).

A study of the variations of the population of Dysdercus fasciatus on cotton and on its wild host-plants is described.

The most important host of D. fasciatus in the Acacia savannah of Northern Rhodesia is Thespesia rogersii, and it is shown that at certain times a general flighting of stainer takes place from this host-plant caused by food shortage or defoliation. Generally a period of food shortage occurs during the earlier months of the year owing to rotting of the old crop and extensive destruction of the early new crop by the larvae of a Cossid moth. This causes an early influx into cotton, which leads to the establishment of a large population in the field at a critical period in the development of the bolls. When the early crop is retained on the trees a continuously increasing food supply is provided, and this first movement does not take place. A second movement from Thespesia, which is largely due to defoliation, begins generally in June. It has been shown that a second influx into cotton coincides with this later movement from Thespesia. A late influx such as this is of little practical importance since the greater part of the crop is picked in May and June.

The observations recorded indicate clearly that the movement of D. fasciatus into cotton is not due to any attraction exercised by the crop but is caused by a forced movement of stainers from Thespesia rogersii.

Colony densities of Acromyrmex landolti fracticornis (Forel) were found to vary in habitats of introduced forage grasses in central Paraguay. Colony densities were found to be positively correlated with basal grass coverage and the amount of grazing damage. The ants preferentially harvested tender grass blades that showed little or no previous damage by other invertebrates. Colony densities and the amount of grazing damage by the ants showed negative correlations with the amount of grazing damage by other invertebrates. Preferences were determined for 13 species of exotic forage grasses. In both laboratory and field tests, Digitaria smutsii and Panicum maximum were selected significantly more often than other species, and Pennisetum purpureum, P. ciliare and Brachiaria decumbens were selected significantly less often. The preferences observed in the laboratory were also observed in field colonies. The importance of these factors in determining colony density and their practical implications on the Paraguayan cattle industry are discussed.

As part of a research project directed at the genetic control of Teleogryllus commodus (Wlk.) in Australia, hybridisation studies have been carried out between T. commodus and the sibling species T. oceanicus (Le Guillou). A cytological examination of a hybrid strain (male progeny of T. commodus × T. oceanicus backcrossed to T. oceanicus) was made in the F4 generation when meiotic stability had been reached. The karyotype was very similar to that of T. oceanicus, suggesting that only those combinations in which the chromosomes were structurally homologous to T. oceanicus survived. But the stridulation pattern of the hybrid males, intermediate between that of the two parental species, and a consistent sex ratio of 2:1 in favour of the males, indicate profound genetic differences from T. oceanicus. These effects are attributed to introgression, with chromosomal material from T. commodus being incorporated in the T. oceanicus genome as an outcome of the initial hybridisation of the two species.

This paper records a number of parasitic and phytophagous species of Chalcididae that have been reared in U.S.S.R. during recent years. The material was partly collected by the author herself, or received for identification from various persons and institutions.

In the following paper is given a list of cotton pests of Papua and New Guinea, with some notes on distribution and behaviour. The list makes no pretensions to being complete, but might prove useful in the event of cotton-growing being extended in that region.

In August 1925, instructions were received to accompany Mr. G. Evans, C.I.E., then Director of Cotton Culture to the Queensland Government, on a tour of cotton areas potential and actual in Papua and the Mandated Territory of New Guinea.

We sailed from Brisbane on 13th August and returned on 30th October. Of the short time at our disposal some 40 odd days were spent at sea. In consequence, the time available for collecting entomological material was not as much as might have been desired.

Hofmannophila pseudospretella (Stnt.) is a very widespread and common omnivorous scavenger in Britain. It is able to digest keratin and, while rarely occurring in large infestations, has a nuisance value as a textile pest in dwellings. It is commonly found breeding in birds' nests and dry organic débris likely to be found in attics and roof spaces, and mature larvae wandering from the feeding site are probably the only cause of damage to domestic textiles which, according to our records, are principally carpets.

A method of maintaining cultures in the laboratory and obtaining standardised larvae for mothproofing tests is described.

Adequate protection against newly hatched larvae was given by 0·1 per cent. Dielmoth (25 per cent, dieldrin) and 1·0 per cent. Mitin FF (an unknown percentage of N-(3,4-dichlorophenyl)-N′-2-(2-sulpho-4-chlorophenoxy)-5-chlorophenyl urea, sodium salt), while six-week-old larvae were not controlled by 0·15 per cent. Dielmoth or 1·0 per cent. Mitin FF. No protection against larvae in the wandering stage was given by Dielmoth in concentrations up to 0·63 per cent, or by 1·0 per cent. Mitin FF.

Both six-week-old and wandering larvae were controlled by 5·0 per cent. Mystox B (20 per cent, pentachlorophenol) and the latter also by 4·0 per cent. Mystox LPL (100 per cent, commercial pentachlorophenyl laurate).

Four models are presented which represent the four combinations of two trap types (food-baited or pheromone-baited), each containing either insecticide or chemosterilant. These were then modelled in combination to determine which combinations might be useful for controlling arthropod pest species in which the virgin females produce sex pheromone which attracts males. The most promising results occurred in combinations involving different trap baits but the same pesticide type, i.e. where one trap contains food bait while the other contains sex pheromone, and both contain either insecticide or chemosterilant. This conforms to the principle of complementarity of control methods and at the same time avoids the interference which would occur if insecticide was used in one trap type and sterilant in the other.

Aphid species found infesting sugar-beet in Tasmania were Aphis craccivora Koch, Aulacorthum solani (Kalt), Macrosiphum euphorbiae (Thos.) and Myzus persicae (Sulz.). The activity of infective alatae over plots of sugar-beet established by sowing at different densities and arrangements to produce 12 treatments was gauged by recording the numbers of plants which became affected with virus yellows symptoms. The incidence of yellows increased as plant density decreased and as plant arrangement altered from rectangular to more square patterns. A regression equation of the form: where a, b, c and d were constants and x and y the intra- and interrow spacings, respectively, accounted for 92% of the variation produced by the 12 treatments. These results indicate that the incidence of virus infection in row crops resulting from aphid flight activity may be manipulated through altering plant density and arrangement.

The effect of DDT applied to cotton plants four times at 10-day intervals at a rate of 1 lb. active ingredient per acre per application against Hemitarsonemus latus Banks was studied at Serere Eesearch Station, Uganda. DDT applied as a 10 per cent, dust, or in a spray from a 50 per cent, wettable powder increased the damage caused by the mite, while DDT applied in a spray from a 25 per cent. miscible liquid decreased it.

Another trial using a DDT miscible-liquid spray applied at intervals of 10, 15 and 20 days at 1 lb. active ingredient per acre per application demonstrated partial control of the mite. However, when spraying ceased, tea-mite damage increased. At the final count all spray intervals showed significantly less damage than the control and there was an over-all significant difference between spray treatments and the control. In both trials the number of mite-infested plants increased in an exponential manner with time.

It is not considered that the present recommended practice of applying DDT four times, at 15-day intervals, in a spray from 25 per cent, miscible liquid at 1 lb. active ingredient per acre will cause an increase of the mite on peasant-grown cotton in Uganda, although it will only partially control any infestation of it that is present.

In preparing his first synopsis of the African species of Culex (Bull. Ent. Res., ii, pt. 3, Oct. 1911) the writer relied almost entirely upon characters of coloration for the separation of species, and had made no study of the male genital organs; at the same time it was pointed out that the group of species allied to Culex invidiosus required much additional study before their classification could be regarded as satisfactory. It is now possible to give in full the results of further study of the African species of Culex of the pipiens and invidiosus groups. It has been found that, in these groups at least, the species can most readily be separated by means of the male genitalia, and also that one or two names which had previously been sunk as synonyms must in reality stand as good species. In the present contribution figures are given of the male genital organs of eleven species; these, together with the four already illustrated (Bull. Ent. Res., iv, pt. 1, May 1913) comprise all the African Culex with the exception of (1) those with a banded proboscis; (2) those with characteristic leg markings, C. tigripes and C. tipuliformis; (3) C. pruina, which is described below; (4) C. didieri, N.L., and C. pygmaeus, N.L., which the writer is unable to recognise; and (5) those with the pale markings of the abdomen situated towards the apices of the segments. As before, all the figures have been prepared by Mr. A. J. Engel Terzi with very great care and accuracy, and I am much indebted to him for his assistance in this difficult piece of work.

The mean hunger-cycles of G. swynnertoni and G. pallidipes have been studied in the field by marking tsetses with cut proboscidae, which have been released and subsequently recaptured.

The length of time that hungry flies are able to survive before dying from starvation varies with the season, probably according to the amounts of reserve fats and atmospheric humidity.

The mean hunger-cycle also varies with the season and correlates significantly with the evaporation rate or other measurements of humidity. The variation of temperature experienced in these experiments was not sufficient to have any appreciable effect on the hunger-cycle.

G. pallidipes, a thicket haunting fly and larger than G. swynnertoni, a thorn bush species, frequently than the latter under moist conditions, but frequently under adverse conditions.

Smaller individuals probably feed more frequently than larger individuals.

Capture rates of insectary-reared female Aedes albopictus (Skuse), Anopheles quadrimaculatus Say, Culex nigripalpus Theobald, Culex quinquefasciatus Say and Aedes triseriatus (Say) in CDC-type light traps (LT) supplemented with CO2 and using the human landing (HL) collection method were observed in matched-pair experiments in outdoor screened enclosures. Mosquito responses were compared on a catch-per-unit-effort basis using regression analysis with LT and HL as the dependent and independent variables, respectively. The average number of mosquitoes captured in 1 min by LT over a 24-h period was significantly related to the average number captured in 1 min by HL only for Cx. nigripalpus and Cx. quinquefasciatus. Patterns of diel activity indicated by a comparison of the mean response to LT and HL at eight different times in a 24-h period were not superposable for any species. The capture rate efficiency of LT when compared with HL was ≤15% for all mosquitoes except Cx. quinquefasciatus (43%). Statistical models of the relationship between mosquito responses to each collection method indicate that, except for Ae. albopictus, LT and HL capture rates are significantly related only during certain times of the diel period. Estimates of mosquito activity based on observations made between sunset and sunrise were most precise in this regard for An. quadrimaculatus and Cx. nigripalpus, as were those between sunrise and sunset for Cx. quinquefasciatus and Ae. triseriatus.

Interspecific competition between an introduced parasitoid species aimed at controlling a herbivorous pest species and a native parasitoid parasitising the same host may influence the success of classical biological control programmes. In Kenya, interspecific competition between an introduced and a local parasitoid on two diamondback moth populations (DBM, Plutella xylostella) was investigated on two different host plants. We tested simultaneous and delayed competition of the local parasitoid Diadegma mollipla Holmgren and its exotic congenus D. semiclausum Hellen on a newly aquired DBM host plant (snowpea) in the laboratory. Under simultaneous competition, D. mollipla produced more progeny than D. semiclausum on snowpea. A head start of D. Mollipla, of four and eight hours before its congenus was introduced, resulted in a similar number of progeny of both species. In delayed competition (time intervals of 24 h, 48 h and 72 h), progeny production was similar for both parasitoids when the time interval was 24 h, irrespective of which species parasitized first. More progeny was produced by the species which attacked first, when the time interval was greater than 24 h, although it was only significant at 72 h. Competitive abilites of both parasitoids on the new host plant differed largely between laboratory and semi-field conditions. The influence of two host plants (snowpea and cabbage) on competition was studied in the greenhouse with different host and parasitoid densities. Parasitism levels of D. semiclausum were significantly higher than those of D. mollipla, regardless of host plant, host and parasitoid densities, but progeny production of D. mollipla on snowpea was still slightly higher than on cabbage. As compared to the confinement of parasitoids and larvae to small containers, D. mollipla parasitized very few larvae in the cages. Competitive ability of the two parasitoid species tested was influenced both by the density of the searching females and by parameters related to either the host plant and/or the herbivorous hosts.

The morphology of the antennae, caudae and wingbuds of Diuraphis noxia (Mordvilko) was used in conjunction with ratios between antennal segment lengths to draw up a key for diagnosis of the instars.