Egg parasitoids attacking economically important pod-sucking Hemiptera on cowpea were collected in Nigeria and Tanzania. The three coreid hosts, Anoplocnemis curvipes (F.), Clavigralla tomentosicollis Stål and C. elongata Sign., and the two alydid hosts, Mirperus jaculus (Thnb.) and Riptortus dentipes (F.), form a pest complex that attacks grain legumes across Africa. Parasitoids attacking eggs of C. tomentosicollis were monitored on farmers' fields at a locality in northern Nigeria. Parasitism rose from low initial levels to maxima of 62% in 1978 and 51% in 1979. This mortality did not keep host populations below the economic injury level. The egg parasitoid complex of C. tomentosicollis was dominated by the scelionid Gryon gnidus (Nixon), while the encyrtids Ooencyrtus patriciae Subba Rao and O. kuvanae (How.) parasitised a large proportion of host eggs at times. Small numbers of Gryon fulviventris (J. C. Crawford) and the eupelmids Anas tatus spp. were reared. Observations on the biology and behaviour of O. patriciae are presented. This species occurred in both Tanzania and Nigeria and attacked all hosts studied. Rearings of all these parasitoids and also another species of Gryon, a species of Baeus and two species of Telenomus from eggs of the five species of Hemiptera are reported.

(1) Aèdes vigilax migrates for long distances and together with Mucidus alternans disperses over considerable areas under favourable physiological conditions.

(2) Migrations are only undertaken when suitable winds make dispersal possible ; north-westerly winds distribute, under suitable atmospheric conditions, untold numbers of A. vigilax all along our foreshores.

(3) In summer the appearance in large numbers of both A. vigilax and Mucidus alternans heralds the approach of a storm.

(4) The presence of mosquitos found in wide areas in Queensland apparently devoid of water may be explained : (a) By the existence of breeding facilities in tree-cavities and similar breeding-places not visible to a casual observer ; (b) by the prevalence of suitable carrying winds by which mosquitos are blown for short or long distances from their native breeding-places ; (c) by extreme localisation of mosquitos breeding in small quantities of water mostly inaccessible to the casual observer.

The population density of mealybug species in some South African citrus orchards has increased to pest status in recent years. The characterization of the natural enemy complex and quantification of their contribution to the control of Planococcus citri (Risso), Pseudococcus longispinus (Targioni-Tozzetti) and Pseudococcus calceolariae (Maskell) on Citrus limon (L.) and Citrus reticulata (Blanco) was investigated through intensive sampling. Eight primary and four secondary parasitoids, and two predator species were identified from P. citri and P. calceolariae. Anagyrus pseudococci (Girault) and Coccidoxenoides peregrinus (Timberlake) were the most common species, accounting for 44% and 21% of the total. Of the five primary parasitoids reared from P. longispinus, A. pseudococci and Anagyrus sp. were predominant, comprising 41% and 30%. Nymphal and adult parasitism (range = 0–26% vs. 0–66%) and predation (range = 0–5.6% vs. 0–4.1%) varied significantly between host trees and mealybug species (P < 0.001). The numbers of nymphal instars and adult stages of P. calceolariae and P. longispinus and the nymphal stage of P. citri that were parasitized and killed by predators correlated significantly with the total number of hosts on which they acted (P < 0.01), suggesting a density-dependent association. Laboratory bioassay of nine contact insecticides (methidathion, methomyl, methyl-parathion, parathion, profenofos and prothiofos) against C. peregrinus indicated that all were highly toxic, causing 98–100% mortality in < 6 h of treatment. The IGRs fenoxycarb and triflumuron did not cause significant parasitoid mortality (P > 0.05). However, a mixture of pyriproxyfen and mineral oil caused a marginally significant mortality (P < 0.05).

The relationship between abundance of Dolichoderus thoracicus (Smith) and damage to cocoa pods caused by Conopomorpha cramerella Snellen was examined in a series of experiments. Pods were harvested from ant-abundant and ant-scarce plots and categorized into fully extractable, partially extractable and unextractable, the last category reflecting the most severe degree of C. cramerella infestation. An abundance of D. thoracicus was associated with significant reductions in the percentage unextractable pods but had little or no influence on the other two categories. Mean percentage pods infested was generally kept below 50% in ant-abundant plots and mostly exceeded the 50% level in ant-scarce plots. Other studies were: a survey of individual pods relating rate of infestation by C. cramerella to D. thoracicus abundance, an experiment which examined the effect of D. thoracicus exclusion on the rate of C. cramerella infestation, and a count of exit holes made by emerging prepupae of C. cramerella in relation to varying degrees of D. thoracicus abundance. The results showed a clear negative effect of D. thoracicus abundance on C. cramerella infestation rate. The results also indicated that the protection conferred by D. thoracicus was largely confined to the particular pod on which it was present. Rat damage, monitored as a subsidiary study, was higher in ant-scarce plots throughout the study period.

The movement of foragers of two species of Australian, subterranean, mound-building termites, Coptotermes lacteus (Froggatt) (Rhinotermitidae) and Nasutitermes exitiosus (Hill) (Termitidae), was investigated in their natural habitat using artificial feeding sites along trenches dug to mimic natural forager tunnels that radiate out from the central mound-nests. Termites were dyed by self-feeding on cardboard soaked with histological fat-stains on one or two trenches and then termites were collected from other feeding sites at two and four weeks after the fat-stains were placed. At two and four weeks after marking commenced, 60–75% of marked termites were found in trenches containing the marked paper, and 2–16% were found in trenches on the opposite side of the nest. The proportion of marked termites in a sample was three to eight times greater in the trenches containing the marked paper relative to other trenches. Although difficulties with fat-stains used as markers might explain some of the observed patterns, it is evident that C. lacteus and N. exitiosus foragers do not move randomly between feeding sites in their natural habitat.

To be effective, management strategies of invasive alien species cannot ignore their spatiotemporal behavior particularly those exerting serious damages to human activities. The black planthopper Ricania speculum is an Asian insect that has been reported as an alien invasive species in Italy, where it threatens local plant diversity, including important crops. In our work, we analyzed the activity rhythms of this species through circular statistics and the efficiency of chromotropic traps to capture adult individuals. Captures were carried out in central Italy, where the black planthopper is showing a remarkable range expansion, after its first discovery in 2009. We observed that the species was mainly crepuscular, with a high intersexual activity overlap. Activity rhythms changed between July–August and September–October, with changing heliophany, but peaked at sunset and were the lowest in the second half of the night and early morning. The insects were mostly caught by green traps, particularly in September, which is the period of egg-laying inside the leaves; conversely, orange ones were avoided, and yellow ones captured proportionally to their local availability. Strategies for controlling this species should consider concentrating trapping effort during the activity peak, using green sticky traps to enhance the capture success of each trap, with the lowest impact over non-target species.

From many parts of the world, but especially from South Asia and Africa, the Imperial Institute of Entomology receives an increasing number of Chalcidoidea, many being important as parasites of noxious insects, but mostly still very little known or even undescribed. The study of all these varied and often difficult species will be the work of many students on parasitic Hymenoptera. For our part we intend to publish a series of notes under the above title, alternatively with notes on African Chalcidoidea, as contributions to a knowledge of the most important or interesting species, the large majority of which have been bred.

In September 1923 I was asked by Dr. C. M. Wenyon to undertake the breeding of the tick, Ornithodorus moubata, female specimens of which were sent to the Wellcome Bureau by Dr. Kelesberger from the Belgian Congo. This gave me an opportunity of carrying out a series of experimental investigations on the biology of the tick which were continued till August 1924. The results obtained from the subject of this paper

Oil palms in West Africa are periodically subject to somewhat serious attacks by Coelaenomenodera elaeidis, Maulik, a beetle of the family HIspidae, which mines the leaves. From the early stages of this beetle Mr. G. S. Cotterell, Assistant Entomologist, Gold Coast, has bred several Chalcidoid parasites, which were forwarded to the Imperial Bureau of Entomology and form the subject of the present paper.

A wild-type black-eyed strain (PALA DR) and a mutant white-eyed strain (S104) of Anopheles gambiae Giles were used to determine whether nulliparous mosquitoes of this species are polyandrous. White-eyed females were given the opportunity to mate with black-eyed and white-eyed males. As the white-eye gene is recessive and is located on the X chromosome the presence of both white- and black-eyed females in a female's egg batch denotes that she mated with males of both types. Three out of 52 egg batches gave rise to both white-and black-eyed females. Only a proportion of multiple matings can be detected in this way; those involving males of only one type go undetected. It is estimated that, under the conditions prevailing during the experiment, 12% of nulliparous A. gambiae are polyandrous.

Lutzomyia lichyi (Floch & Abbonenc) is a suggested secondary vector of Leishmania in Colombia. Taxonomically, L. lichyi is very closely related to the L. longipalpis (Lutz & Neiva) species complex. Male members of the complex can be distinguished by their sex pheromones which are produced in papules found grouped together in pale patches on tergites 3 or tergites 3 and 4. Male L. lichyi also have papules, very similar in appearance to those of the L. longipalpis species complex but distributed on tergites 4, 5, 6 and 7. Chemical analysis of male L. lichyi hexane extracts has revealed the presence of two novel oxygenated methylsesquiterpenes. The two major oxygenated terpenes found in the extract of L. lichyi males are tentatively characterized as a primary and tertiary alcohol. The mass spectrum of the proposed primary alcohol is very similar to the published mass spectrum of 3-methyl-α-himachalene, the sex pheromone produced by the Jacobina chemotype of the L. longipalpis complex. The mass spectrum of the proposed tertiary alcohol also has similarities to the 3-methyl-α-himachalene sex pheromone.

The influence of a deep river valley system on the distribution of dispersing Aedes mosquitos was studied during 1958–59 in the vicinity of Edmonton, Alberta, Canada. Mosquito breeding within an area extending two to three miles beyond the city limits was prevented by anti-larval measures, and almost the only remaining breeding places were situated on the plains several miles to the north-west and south-east, yet considerable numbers of mosquitos appeared every spring in that part of the city included in the valley-ravine system of the North Saskatchewan River. Previous work had suggested that mosquitos dispersing across the plains were collected by the valley-ravine system and entered the city by passing down the main valley. The present paper attempts to account for this directed dispersal in terms of the behaviour of Aedes mosquitos in response to certain physical factors in the environment. The species mainly concerned were Aedes cataphylla Dyar, A. fitchii (Felt & Young), A. excrucians (Wlk.) and A. stimulans (Wlk.).

The initiation of dispersal flight downwind across the plains at twilight was observed. This took place soon after emergence and was not prevented by moderate winds. It was shown experimentally that neither high wind speeds nor turbulence inhibited the flight of newly emerged Aedes mosquitos, but that individuals several days old were reluctant to take flight in turbulent conditions. Since wind speeds on the plains were generally higher than those in the valleys, these reactions would tend to confine older mosquitos to the valleys while not preventing dispersal of newly emerged mosquitos across the plains.

The direction of the initial dispersal flights from the breeding places was observed in mosquitos escaping from rearing cages. Take-off was characteristically into the wind, but re-orientation downwind took place when the mosquitos began to be blown backwards in flight. It was shown experimentally, by releasing mosquitos in the field when the wind was very light, that the preferred direction of flight uninfluenced by wind was towards the lowest part of the horizon, both on the plains and in the valley. This response would tend to cause mosquitos on the plain to fly into ravines and valleys, and thence down-stream within them. Dispersing mosquitos would thus tend to be held by any valleys or ravines in their path.

Swarming was never observed near the pools from which the mosquitos emerged, but was mainly seen in the valley or on the edge of the valley and ravines. Swarming of A. cataphylla took place during the evenings after the initial dispersal. The swarms were predominantly male but mating occurred during swarming. A cohesive factor seemed to be involved in the behaviour of the swarms, and further dispersal also seemed to occur gregariously; the movement of large male swarms down the river valley was observed.

By the application of optomotor theories of insect flight to previously published data on the flight speed and behaviour of A. aegypti (L.) and A. punctor (Kby.), the relationships between wind speed and permissible heights of flight of these species upwind and downwind were calculated. These relationships were consistent with the observations on dispersal of Aedes mosquitos in the Edmonton area, and could largely explain the mechanism by means of which deep valleys attracted and held dispersing mosquitos.

In contrast to the open plains, the wooded river valley provides a more favourable environment for adult mosquitos. The supply of nectar is greater, saturation deficiency and wind speeds are lower and less variable, and shaded resting sites are more abundant.

Observations on mosquitos in chambers with either vertical or horizontal humidity gradients suggested that the behaviour of Aedes mosquitos is not greatly influenced by humidity.

Field and laboratory experiments were carried out in Ghana on the tsetse fly, Glossina medicorum Aust., to discover the senses used by the fly in finding its host. In laboratory experiments on vision a model locomotive with a black screen attached to it was used as a ‘host’. The flies were stimulated to move by the movement of the screen. When the screen was stopped and started for short periods the increase in activity became less each time the screen was put in motion but the fall off was less rapid than in experiments with continuous movement. The possible significance of this is discussed in the light of the normal habitat of the species in the field.

In the field, G. medicorum did not respond to a moving object more than 25 ft. away but G. morsitans Westw. showed a good response at distances up to 150 ft.

Tethered flies were attracted to the model screen and showed a preference for landing on the lower edge near the centre.

Laboratory experiments using a guineapig and a goat as sources of smell produced no response from the flies but a strong reaction was obtained with the vapour of dilute acetic acid. In field experiments, using cows which were not visible to the fly, a very marked response to the smell of the cows was obtained. Orientation to a source of smell probably involves orientation to air movement and G. medicorum showed a strong upwind orientation in a wind tunnel even when blinded.

It is concluded that G. medicorum, which lives in thicket or forest where visibility is poor, probably responds initially to the smell of a potential host. An upwind orientation would then bring it to the general vicinity of the animal and the final approach might be visual.

Tersilochus obscurator Aubert and Tersilochus microgaster (Szépligeti) are larval endoparasitoids of economically-important stem-mining pests of winter oilseed rape (Brassica napus L.) in Europe. They are difficult to separate morphologically. Their hosts are Ceutorhynchus pallidactylus (Marsham) and Psylliodes chrysocephala Linnaeus, respectively. The parasitoids' taxonomic status, identification, host range and phenology were studied using genetic, morphometric and ecological data. The study used 527 female parasitoids from the UK and Germany, either field-collected in emergence traps or reared from field-collected host larvae. Two morphometric characters, the ovipositor sheath to first metasomal tergite ratio and the percentage of the mesopleuron spanned by the sternaulus, were measured. A 440 bp section of mitochondrial DNA cytochrome oxidase subunit I (COI) gene was sequenced from 35 parasitoids reared from C. pallidactylus, 20 reared from P. chrysocephala and individuals from two outgroups, Tersilochus heterocerus Thomson and Phradis interstitialis Thomson. Distinct and invariable COI sequences corresponded exclusively to each parasitoid group, confirming that T. obscurator and T. microgaster are discrete species. Measurements of host-reared and COI-sequenced specimens indicated that the ranges of both morphometric characters overlapped between species. Using these ranges as criteria, all but 3.6% of UK specimens and 2% of German specimens were identifiable to species without reference to host or phenology. There were differences in emergence phenology in the UK, adult T. microgaster emerging from winter diapause by 29 March 2000, T. obscurator emerging between 12 April and 24 May 2000. The value of molecular techniques in the identification of closely-related parasitoid species is discussed.

Six trials with an unpurified suspension of Heliothis armigera nuclear polyhedrosis virus (NPV) against Heliothis armigera (Hb.) larvae on sorghum (five trials) and on cotton (one trial) during 1971–73 are described. Commercial preparations of H. zea NPV and of Bacillus thuringiensis were included in two of the trials. H. armigera NPV was as successful as a standard insecticide in preventing losses of sorghum in one trial. Lowering the rate of NPV reduced the control of H. armigera larvae. There was no difference in control achieved by spraying in the morning or in the evening. Spraying every second or every third row (relying on natural spread of the virus) reduced control. Low concentrations of molasses (0·6%) made control by 100 larval equivalents (L.E.) per hectare as good as that by 200 L.E. per hectare without molasses. Neither the commercial H. zea NPV nor the Bacillus preparation was as effective as the local virus. The local virus was reasonably effective against H. armigera on cotton at very high rates and with molasses. It was not as damaging as carbaryl to populations of egg parasites and predators, but the predators did not control damaging populations of aphid and Jassid on the virus-sprayed plots.

For the biological study of Tachardia lacca, Kerr, it is of importance to have, so far as possible, a complete knowledge of all the insects that live in relation with it—predators and parasites of the Coccid, parasites of the predators and hyperparasites. This biological complex begins to be better known, owing to the studies of several entomologists in India, especially at the Indian Lac Research Institute at Namkum.

A microburette made from glass capillary tubing is mounted on the mechanical stage of a microscope and filled with insecticide solution to a point at which the meniscus is in the field of the microscope. The magnified images of the meniscus and a calibrated micrometer scale in the eyepiece are projected on to a small screen mounted close to the tip of the microburette so that the scale and the insect being dosed can be seen simultaneously. This feature renders the apparatus particularly suitable for topical application work in which accurate positioning of the dose on the insect is required. When an insect, held in a suction device described, is applied to the tip of the burette, the solution flows out unaided, and stops immediately the insect is removed. With the microburette described, doses from 0.005 to 0.035 μl. can be dispensed to within ±0.00035 μl. The apparatus can be made to cover several other dosage ranges, either lower or higher, by simple modifications which are discussed.

Liothrips mikaniae (Priesn.) comb. n. is one of the most promising biological control agents for Mikania micrantha, a sprawling composite vine native to the Neotropics which is a serious weed of plantations in South-East Asia. A description and illustrations of the adult and larvae of this thrips is followed by details of the life-history, culture technique, host specificity (including laboratory studies demonstrating oligophagy) and natural enemies. It is recommended for introduction to South-East Asia.

Biconical, F3, and wind oriented (WOT) traps, and black cloth targets, baited with the odour attractant swormlure-4, were assessed as catching and killing devices for the New World screwworm fly, Cochliomyia hominivorax (Coquerel), in Mexico. Among the traps, the WOT was significantly better than the others, with a mean catch 2.7 and 86.4 times better than those of the biconical and F3, respectively. Release of swormlure-4 could be reduced from the standard 10 ml'day to 2 ml'day without a reduction in the numbers caught in a WOT. Use of electric nets demonstrated that a large visual target was not necessary for the precise location of a swormlure-4 source by C. hominivorax. Target colour was important with respect to the landing response on targets: in a two-choice situation, flies landed much more frequently on black than on blue or yellow, and more on these two colours than they did on white. C. hominivorax tend not to circle a target before landing on it: about 75% of the flies caught on a combination of electrified black target plus electric flanking net were caught on the target. The potential for use of insecticide-impregnated cloth targets in suppression of adult C. hominivorax is discussed.

1. All material was reared under constant conditions of temperature, light intensity and relative humidity. Two relative humidities were used—very wet and very dry. In some cases various coloured backgrounds were used. All material was solitaria, and was kept isolated.

2. Average weights were calculated from weighings made at all periods within the stadia, and thus represent the weights at the mid-points of the stadia.

3. The figures could not be fitted to the theory of a progression factor of 2.

4. Females are on the average 50 per cent, heavier than males even in the third instar; the sexes can probably be distinguished in this way much earlier.

5. The first three stadia are of about the same length; the fourth is longer, the fifth much longer.

6. The percentage rate of growth between the mid-points of successive stadia is of the same order for all pairs, though somewhat lower for the first and last pairs.

7. Hoppers kept in a very dry atmosphere are much lighter than those kept wet —proportionally more so in the later than in the earlier instars; on the other hand each stadium is lengthened—proportionally more so in the earlier than in the later stadia; the percentage rate of growth is just half that of hoppers kept wet.

8. The findings of Faure in regard to the causes of differences in coloration were fully confirmed.

9. The occurrence of a sixth instar in the females is due to an inherited factor.

10. This “ extra ” instar may represent an extra morphological third instar or an extra morphological fourth instar.