An in vitro test, based on the molasses sandwich-bait test, for mass screening of new compounds for general insect repellency is described. This is followed by a detailed account of a laboratory technique for comparing the initial potency of contact repellents for the stable fly Stomoxys calcitrans (L.).

Methods for rearing S. calcitrans of standardised aggressiveness and making comparative assessments of contact repellents against this fly are described. For initial potency, a standard area of the treated close-clipped abdominal skin of mice lying outside the cage was exposed through an orifice to standardised flies. A treated 0·5-cm-wide screen was incorporated as a border round the exposed area of treated skin so that flies biting the mouse were obliged to make tarsal contact with repellent. Using this method, and the organdie bag x human hand method for determining persistence on an inert substrate, each of the following repellents was compared with butyl 3-methylcinchoninate, a new repellent for S. calcitrans:

dimethylphthalate; 2-ethyl-1, 3-hexanediol; butoxypolypropylene glycol; dibutyl succinate; N,N-diethyl-m-toluamide; di-n-propyl isocinchomeronate; 2,3,4,5-bis (Δ2-butenylene)-tetrahydrofurfural; 2-hydroxyethyl n-octyl sulphide and N-benzoyl piperidine.

In each case butyl 3-methylcinchoninate was found to be superior. In the initial potency tests, the 50% repellency application rate was found to lie between 0·002 and 0·007 mg/cm2, while on organdie, rates of 0·2, 0·4, 0·8 mg/cm2 gave mean protection periods of 9, 19 and 34 days, respectively.

The identity is established of Palexorista quadrizonula (Thomson), an African Tachinid parasite of Lepidopterous pests, including the armyworms (Spodoptera spp.). The species is described and the known hosts recorded.

In 1964–65, breeding sites of the tsetse fly G. tachinoides Westw. near Nsukka in south-eastern Nigeria were found in peri-domestic situations (particularly beneath stacked coco-yam tubers and at the base of fences of pig enclosures) and in adjacent farmland (particularly beneath banana and coco-yam plants, under Lantana camara, at the base of farmland fences and around derelict farm buildings). Between them, these sites provide moisture conditions suitable for year-round breeding of G. tachinoides and are not exposed to unsuitably high temperatures (>90°F) for long periods. The night-time resting sites of G. tachinoides in three villages five miles east of Nsukka were sought between May and November 1966 using ordinary torchlight. The most popular resting-sites were dried fronds of oil and coconut palms used for fencing pig enclosures, but a few flies also rested on man-made objects in the villages and on vegetation nearby. Most flies were resting less than two feet above ground level. Day-time observations confirmed the night-time findings. G. tachinoides could probably be controlled, if not eradicated, in the Nsukka area by two applications, a fortnight apart, of DDT emulsion concentrate to pig enclosure fences and pig styes up to a height of 2–3 ft during March–May when the fly population is most concentrated around confined pigs.

Dispersal of the larvae of the cattle tick Boophilus microplus (Can.) was studied in connection with problems of controlling and eradicating this pest and bovine babesiosis in New South Wales. Larval ticks were recovered by pressing flannelette-covered boards on to the pasture or litter surface, or sampling with cattle. Many of these larvae were capable of completing parasitic development.

Strong winds were an important factor in determining the distance travelled, as the longest journeys in pasture were for the most part in the directions in which the larvae would have been carried by recorded strong winds. Much of the dispersal is accomplished when larvae are transferred from one grass blade to another moving in the wind, but a great number of airborne larvae were captured on tanglefoot-covered traps. Movement by wind was clearly demonstrated over short pasture, up to 100 ft and possibly as far as 260 ft from the point of hatching. In long grass one larva travelled 83 ft, but in scrub and forest the greatest distance travelled was 15 ft. Many larvae that travelled long distances were capable of completing development on cattle.

Tick larvae could be transported by casual hosts and then dropped in a viable condition. A horse carried larvae for 900 ft, a rat and cockerels 100 ft, a magpie in flight 600 ft, and a pigeon in flight half a mile. A horse dipped six days earlier in ethion dropped live and viable larvae after transporting them 150 ft.

Security has been improved against the movement of larvae from the Cattle Tick Research Station, Wollongbar, New South Wales, to neighbouring properties, and from Queensland into New South Wales, by widening existing buffer zones to 330 ft. Inspectoral staff are now required to spray themselves and their horses before re-entering New South Wales from the buffer zone.

Infestations of the rice gall midge Pachydiplosis oryzae (Wood-Mason) in Ceylon were studied in 1968. The three larval instars, the prepupa and pupa are described. Total development time is 18–22 days. Dissection of infested rice seedlings showed that first-instar larvae move in 6–12 h from the leaves where they hatch to the shoot apices to which they are specifically attracted, without boring into plant tissues. Larvae feed at the base of the growth cone throughout their development; if more than one larva reaches a shoot apex only one individual survives to maturity. Gall formation results from suppression of the growth cone, development of radial ridges from the innermost leaf primordium just above the level of the posterior end of the larva, and then an elongation of the leaf sheath. Death of the larva, achieved experimentally by means of diazinon or fenitrothion applied to the soil, up to and including instar 2 was followed by renewed activity of the growth cone, but after the same treatment during instar 3 the growth cone was not re-activated. The development of the gall is seen as being due to diversion of nutrients from the growth cone to the midge larva, and possibly by substances produced by the first-instar larva and prepupa which stimulate growth of the radial ridges and gall elongation, respectively. Firstinstar larvae develop only in active shoot apices; thus development proceeds normally in the terminal apex, but is inhibited in the inactive axillary shoot apices. Under high population pressure all shoot apices become infested, but larval dormancy results in staggered gall formation and adult emergence. Larval dormancy in inactive axillary shoot apices may explain seasonal carry-over of the pest.

Albedo (the inner, white part of the rind) of the grapefruit (Citrus parodisi) and the flowers of the garden hibiscus (Hibiscus rosa-sinensis) were analysed for the presence of chemo-stimulants for the leaf-cutting ants Atta cephalotes (L.) and Acromyrmex octospinosus (Reich). Two distinct types of chemical substances in grapefruit albedo (unabsorbed sapids from a cation-exchange resin I.R. 120, and the total lipid fraction) were significant arrestants for Atta cephalotes, whilst five types of chemical substances (absorbate on the cation-exchange resin I.R. 120, unabsorbed sapids from the same resin, the total lipid fraction, absorbate on a polyamide resin, and neohesperidosides) arrested Acromyrmex octospinosus. For both ant species, the unabsorbed sapids from the polyamide resin appeared to be the most attractive of the relatively refined fractions. A preliminary analysis showed a similar situation for hibiscus flowers.

Both ant species preferred young to older grapefruit leaves. There appears to be a chemical basis for this, and in the case of A. octospinosus there was evidence of the existence of repellents in the older leaves and in grapefruit flavedo (the outer, yellow part of the rind).

Substantial heterogeneity in preferences was detected in a given nest from day to day, between different nests of the same species, and between the two species. It is suggested that this is attributable to social phenomena evolved by the ants.

Female tsetse flies (Glossina morsitans Westw.) were more active in an experimental chamber in the laboratory: (a) at high than at low temperatures, (b) in high than in low humidities, and except at high temperatures, (c) when hungry than when replete. Flies were also more active in the chamber when a small area of black surface (1·6%) was present than when a larger black surface (12·8% or 50%) was available. Both black and white surfaces were provided in all experiments, and over the temperature range 25–40°C flies settled on black more frequently than would be expected by chance. This preference for a black resting surface was most marked when the flies were most active: (a) above 35°C in all experiments, (b) at high humidities with teneral flies, and (c) when the flies had not fed. Flies settling on black usually rested longer than those settling on a white surface.

Phlebotomine sandflies were collected simultaneously at ground level, 25 ft and 40 ft in an area of medium bush in British Honduras (Belize).

Flies were captured on human bait, with rat-baited oil-traps and with miniature light-traps, and some resting individuals were collected at each level. One species of Brumptomyia França and 18 of Lutzomyia França & Parrot were obtained. Brief notes on some of these species are given.

Miniature light-traps provided the widest range of species, were the most satisfactory means for collecting Brumptomyia, L. steatopyga (Fairchild & Hertig) and L. carpenteri (Fairchild & Hertig), and yielded new information on the flight activities of L. deleoni (Fairchild & Hertig) and L. panamensis (Shannon).

Most species collected were found to be predominantly arboreal in habit, L. permira (Fairchild & Hertig) and Lutzomyia sp. P being almost exclusively so. Some species (L. panamensis, possibly L. geniculata (Mangabeira) and L. bispinosa (Fairchild & Hertig)) live amongst the foliage but descend to the forest floor to seek blood-meals. A few species (L. steatopyga, L. deleoni and L. olmeca (Vargas & Díaz Nájera)) are active mainly near the ground, though the occasional specimen may be carried much higher.

L. olmeca is the principal vector of rodent leishmaniasis in British Honduras. In the present study, no evidence was obtained to incriminate any other species of Phlebotomine as an insect host for Leishmania mexicana, and the mode of transmission of the parasite to man remains obscure.

A new Anopheles species of the subgenus Cellia Theobald is described from a female caught at ultraviolet light in northern Nigeria, and named A. deemingi. A description is also given of an atypical female adult of A. pretoriensis (Theobald).

Survival and age-specific fecundity rates are given for samples of Glossina austeni Newst. fed on lop-eared rabbits or goats. From these, rm (the innate capacity for increase in numbers) is calculated as being 0·0173 for rabbit-fed and 0·0157 for goat-fed colonies of flies.

The outputs available for disposal from stationary colonies maintained on the two hosts are calculated and the predicted effect of killing the surviving breeding females at various ages is indicated. It is concluded that the weekly output of males, depending on the conditions, could be 20–30% of the number of breeding flies that have to be maintained and that for a given output the number of goat-fed flies that would have to be maintained would be 18–20% greater than the number of rabbit-fed flies. Such small differences in productivity would probably be outweighed by considerations of availability and ease of maintenance of host species in relation to local conditions and costs.

It is believed that the maximum output for colonies of G. austeni has been approached.

This paper is concerned with certain Mymaridae from crop pests in the Far East and the Ethiopian region. Anneckia oophaga gen. et sp.n. was reared from eggs of Sexava in New Guinea, and a key is given for the separation of the genus from other members of the tribe Anagrini. Acanthomymar nigrum gen. et sp.n. is associated with pests of coffee in Uganda and the genus is placed close to Chaetomymar Ogloblin (tribe Mymarini). Gonatocerus brevifuniculatus sp.n. reared from an unidentified scale on Albizia sp. in Pakistan and from Indonesia, Polynema oophaga sp.n. from Tettigoniid eggs in Malaysia, and the previously unknown male of Platypatasson fransseni Ogloblin are described. The original description of Erythmelus helopeltidis Gahan is extended by means of illustrations and Ophiomyia lantanae (Froggatt) is cited as an additional host record. Identification of material from Tanganyika showed the range of Chaetomymar lepidum Annecke & Doutt to extend to that country.

Contarinia coffeae sp.n. is described from specimens reared from Coffea arabica in Uganda, and brief notes are given on symptoms, biology, crop loss and distribution. The larvae develop inside young coffee berries. Blister-like external swellings appear on infested berries and they later rot. The pest is known only from arabica coffee in parts of Western Uganda but may be spreading and could appear in other East and Central African countries.

New evidence on the nature of recession populations of the desert locust, Schistocerca gregaria (Forsk.), and on the nature and role of its outbreaks is presented. It is shown that the hopper bands and swarms reported during the 1963–67 recession differed qualitatively and quantitatively from those characteristic of plague periods and were numerically much smaller than some low density non-swarming populations. Gregarisation frequently occurs in the latter and may be on a scale sufficient to give rise to an outbreak; in turn outbreaks may lead to plague upsurges.

Pediobius furvus (Gah.) (Eulophidae) is a parasite of the pupae of Pyralid and Noctuid stem-borers on graminaceous crops in Africa between 17°N and 17°S. It co-exists with the other pupal parasites Dentichasmias busseolae Heinr. and Procerochasmias nigromaculatus (Cam.) (Ichneumonidae) and Hyperchalcidia soudanensis Steffan (Chalcididae), but it is more abundant below 4000 ft where P. nigromaculatus does not occur. Mating follows a courtship dance, and oviposition occurs in any part of the host pupa. The life-cycle is completed in 18–20 days at 30°C, and up to several hundred adults may emerge from a single host pupa, the most suitable pupae being 2–3 days old at the time of oviposition. Longevity was improved when sucrose was provided as food. Host pupae outside the stem were parasitised, but puparia of Diptera and cocoons of Apanteles sesamiae Cam. (Braconidae) were not parasitised in the laboratory. Pupae formed inside cocoons were not attacked. Pediobius furvus has become established in Madagascar on Sesamia calamistis Hmps, and is considered promising for biological control of graminaceous stem-borers in other countries.

Experiments in the glasshouse have confirmed that spraying virus-source leaves or test plants with mineral oil (liquid paraffin) inhibits transmission of beet yellows virus (BYV) to sugar-beet by Myzus persicae (Sulz.). Spraying M. persicae with oil after feeding on BYV-infected leaves and before transfer to virus-free beet seedlings also inhibited their transmission of BYV. The appearance of systemic symptoms of BYV was not delayed by treatment of the test plants or the aphids with oil. The effects of oil on virus transmission were reflected in adverse effects of oil on the settling behaviour and larviposition of the vector on test plants. It is suggested that coating the stylets with oil inhibits the feeding of aphids in the phloem thereby decreasing the efficiency of BYV transmission. The effects of oil on aphid settling and larviposition suggest that spraying crops with oil may not only reduce the incidence of aphid-transmitted viruses in them but may also diminish the population of potential vectors present in them.

The larvae of three species of bark beetle, Scolytus scolytus (F.), S. multistriatus (Marsham) and Pteleobius vittatus(F.) are described and figured. The larva of S. scolytus resembles most closely that of S. triarmatus (Eggers) but the species appear to be distinct. The larva of S. multistriatus is clearly separated from all other Scolytus larvae so far described. The larva of P. vittatus is most closely related to those of the genera Hylesinus and Leperisinus. The characters of the larvae largely support classifications based on adult morphology and anatomy.

An apparatus for dispensing the eggs of cabbage root fly (Erioischia brassicae (Bch.)) is described. It consists of an ‘Agla’ micrometer syringe, a 2-ml pipette and a 20-mlsyringe connected together by a three-way valve. The eggs are dispensed volumetrically, the standard errors being < ±10% for batches ranging from 30 to 300 eggs. This degree of variation had no measurable effects on the uniformity of pupae from cabbage root fly cultures.

Laboratory studies were conducted on the incubation period of the desert locust, Schistocerca gregaria (Forsk.). When egg-pods were incubated at constant temperature, the duration of the incubation period ranged from 50 days at 19·7°C to 11–12 days at 35–41 °C. The colour of the resulting hatchlings showed dependence on temperature, ranging from grey-white at 41 °C to overall black at 20°C. The minimum temperature at which embryonic development took place was 15·1°C, while the minimum temperature for the hatching sequence was about 20–24°C. The upper lethal limit for embryonic development depended both on temperature and on the duration of exposure of the eggs to that temperature. For example, constant temperatures above 38°C throughout development reduced viability, but exposure to 40°C for six hours each day did not adversely affect development or hatching. Between 15·1 and 35°C the rate of egg development was proportional to temperature; above 35°C the rate appeared to be constant and independent of temperature. Embryonic development was complete when the eggs had experienced 224 degree-days above 15·1°C, except at temperatures in excess of 35°C.