A range of insecticides were tested on a resistant strain of bed-bugs (Cimex lectularius L.) from Israel. Resistance was restricted to organophosphorus compounds. Only some of the phosphorothioate compounds were involved, but there was no simple indication of the resistance mechanism on basis of structure of the compounds.

Nine malathion analogues were tested on the bed-bugs, and relative levels of resistance to them compared with insect strains specifically resistant to malathion. Distinct differences in the bed-bug spectrum suggested that a carboxyesterase was not solely responsible for resistance. This was further supported by the ineffectiveness of triphenylphosphate against malathion-resistance in the bugs.

The F1 progeny from reciprocal mass crosses were tested with malathion. Their response, in both cases, resembled the susceptible type, indicating a recessive autosomal character, a result unique in organophosphorus-resistance. Tests on F2 and backcrosses indicated that a single gene was responsible. Results using fenchlorphos were quite similar and probably the same gene (and mechanism) is involved.

Field studies on the biting habits of Culicoides furens (Poey) were made near Montego Bay, Jamaica, during 1959 and 1960. Details of the experimental design and analysis have been given in the preceding article of this series. C. furens was collected in eight experiments, six on Florida beach, one at East Florida and one at White Bay. Four of the experiments were conducted at sunset, three at dawn and one in the night.

This paper is designed to improve the definition of some Eulophid parasites, mostly of coffee leaf-miners (Leucoptera spp.) and of the web spinner Odites artigena (Meyr.), which are being studied in East Africa. Some of these were previously unknown or without valid names. It is convenient to include a tropicopolitan parasite of Agromyzidae leaf-mining in vegetables and a parasite of a Coleophorid case-bearer from the Bahamas.

In the Elachertine genus Cirrospilus Westw., a key is given for the separation of the African species affecting coffee leaf-miners. These are compared with the European species, and the new species also with its closest American relative. Evidence suggests that the supposed subgeneric divisions cannot be maintained.

In the Eulophinae, Crateulophus Masi is recalled from synonymy and is compared with Sympiesis Först. Relevant species are placed accordingly, and keys are given to species of both genera. A new parasite of Odites is ascribed to Microlycus Thorns., a genus previously known only in continental Europe.

In the Entedontinae, a key is given to the relevant species now placed in Achrysocharis Gir. Derostenus Westw. and some related genera are more closely defined. A new genus is proposed for Derostenus coffeae Ferrière 1936, and a further new genus for another parasite of Leucoptera and its relatives. A recorded but previously unnamed species is placed in Chrysocharis Först., and both this and C. lepelleyi Ferrière are compared with European species of that genus.

The genus Proacrias Ihering 1913, based on the South American species P. coffeae Ihering, has been placed in synonymy with Neochrysocharis Kurdyumov 1912. Attempts to trace the unique type of Perinetia coffeae Risbec 1952 have not met with success.

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.

Rearing experiments with Trogoderma granarium Everts were conducted to determine why the larvae fail to develop in certain pulses. The larvae were unable to penetrate whole grains of any of the nine pulses tested. In flour form, the pulses fell into three main groups. On flours of green, black, Bengal and kabuli grams, and cowpea and pigeon pea, development was as successful and rapid, or nearly so, as on wheat flour and showed little improvement from the addition of yeast. Development on flours of soybean and lentil was markedly slower, and showed marked improvement when yeast was added. By adding increased proportions of balanced diet, it was shown that the performance of larvae on soybean, lentil and even on French bean flours could be improved, but with the last two was not as good as with cellulose. It is concluded that lentils and French beans lack essential nutrients and may also contain a growth inhibitor.

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.

Simulium (Phoretomyia) dukei sp.n., an occasional man-biter, is described and its systematic position discussed. Its larvae and pupae are associated with the prawn Atya africana Bouvier which is the only known host of phoretic Simuliids apart from river-crabs and mayfly nymphs. Four other phoretic species of Simulium are known in West Cameroon, and descriptions of two of them, S. berneri Freeman and S. ovazzae Grenier & Mouchet, are amplified.

This paper reports the results of a field experiment on Florida beach, Falmouth, Jamaica, in which continuous observations were made on the biting rates of Culicoides furens (Poey) (7 707 specimens) and C. barbosai Wirth & Blanton (3 793 specimens) over two 48-h sessions in January 1960. Catches were standardised by the use of correction factors previously calculated. The standardisation experiments also provided additional information on parts of the 24-h cycle, particularly sunrise and sunset.

This paper is one of a series analysing the quantitative effects of various factors on the biting rates of Culicoides furens (Poey) and C. barbosai Wirth & Blanton in Jamaica. It is concerned with the relationship between their biting rates and four meteorological variables: wind speed, temperature, illumination and saturation deficit. The methods used and the full data have already been published.

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.

A simple procedure for mass-rearing Megaselia scalaris (Lw.) is described, and the suitability of one-day-old adults for bioassay of organophosphorus insecticides is compared with that of Drosophila melanogaster Mg., and Musca domestica nebulo F. by exposure to films of parathion, dichlorvos and malathion. LC50 values of Megaselia scalaris for parathion and malathion, but not for dichlorvos, were of a different order to those of the other two test insects. Males were more susceptible than females to parathion and malathion. Mixed populations would therefore be useful in bioassay of organophosphorus compounds, but greater sensitivity would be achieved by using males.

The effects of DDT on the behaviour and mortality of Anopheles gambiae Giles, A. funestus Giles, Mansonia uniformis (Theo.) and Culex pipiens fatigans Wied., entering experimental huts, have been studied with the assistance of gas-chromatographic techniques.

Sixty to 70% of A. gambiae and 70–80% of M. uniformis were deterred from entering verandah-trap huts treated indoors with a nominal dosage of 200 μg/cm2 of DDT active ingredient. Gas chromatographic techniques indicate that the chemical basis of the deterrency was a steadily diminishing outflow of DDT from the hut, either as a dust or vapour, and the build-up of deposit on the untreated overhanging eaves to 0·02 to 0·27 μg/cm2 seven months after treatment. A. funestus was less deterred than A. gambiae and M. uniformis, but the behaviour of C. p. fatigans was almost unaffected by the DDT deposit.

Overall mortalities were highest in A. funestus and M. uniformis, lower in A. gambiae and extremely low in C. p. fatigans.

There was a marked irritant effect of the DDT deposit on recently blood-fed A. gambiae, some 50–70% being driven out of the treated huts. This behaviour occurred to a lesser degree in A. funestus but was absent in M. uniformis and C. p. fatigans. The chemical basis of the irritant effect was indicated to the extent that surviving mosquitoes, that left the treated hut, showed 1·5 ng/insect of DDT. Mosquitoes that died, whether indoors or after leaving the hut, picked up amounts ranging from 7 to 20 ng/insect.

Geromyia gen.n. is erected to accommodate the millet grain midge, Itonida penniseti Felt, 1920, a species that attacks developing grain of bulrush millet, Pennisetum typhoides and other species of Pennisetum. Cecidomyia penniseti Felt, 1920, Itonida seminis Felt, 1921 and Cecidomyia pennisetoides Barnes, 1956 are synonymised under G. penniseti. The male, female and larva are described and illustrated in detail and the life-cycle and seasonal biology are described from field observations at Bambey, Senegal. G. penniseti is recorded from P. typhoides in India, the Sudan, Nigeria, Senegal, Niger and Upper Volta and is provisionally recognised in collections from P. polystachyon and P. pedicellatum in Ghana, Uganda, Madagascar and Nigeria.

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.

An account is given of laboratory studies and field observations in Jamaica and British Honduras on the host-plants, life-history and habits of Saccharosydne saccharivora (Westw.), a major pest of sugar-cane. The original host-plants of S. saccharivora are shown to be two species of grasses, Andropogon glomeratus and A. bicornis. The immature stages of S. saccharivora are described and illustrated; the five nymphal instars may most easily be distinguished by their increasing size, the differentiation of the wing buds and the increasing spinosity of the metathoracic tibia and tarsus. Daily records of individuals of S. saccharivora show the duration of the different stages on fertilised plant cane at c. 80°F to be as follows: egg, 15–19 days; instar 1, 6–7 days; instars 2, 3 and 4, each 4–5 days; instar 5, 6–7 days; adult male, about one week; adult female, up to four weeks. The complete life-cycle took 6½–7 weeks, but was slower on unfertilised ratoon cane. In describing the habits of S. saccharivora, particular attention is given to feeding (feeding probes reach the bundle sheath cells and phloem of the lamina), oviposition (young leaves are the preferred oviposition site) and migration (immigration of adults on to young cane occurred at all times of year).

Seasonal changes in two natural larval populations of Leptoconops becquaerti (Kieff.), a biting sandfly of economic importance in the Caribbean area, are described from studies in 1963–64 near Montego Bay. Aspects of the ecology arising from these observations are included. An attempt is made to relate the seasonal changes in the larval populations to the seasonal distribution of adults, and in addition, a separation is made between the autogenous and anautogenous forms of the insect.

Larvae of both autogenous and anautogenous forms lived together in the same breeding sites and did not appear to differ in their spatial distribution. The two populations studied consisted mainly of larvae associated with the small, autogenous form. Drastic reduction in both populations occurred following events such as wave action and heavy rain that had a mechanical action on the sand in which the larvae lived. The distribution of both forms of larvae was dependent upon the surface elevation with respect to the level of free soil water, since this to a large extent, owing to the upward capillary movement of water, governs moisture content of the surface sand. Elevations between about 9 and 17 in. appeared to be the most favourable. Permanent breeding probably does not occur in sand at elevations greater than about 21 in., though temporary breeding may occur at higher elevations if some other source of moisture (e.g., frequent rain) is available.

In the autogenous form, a prolonged period was spent in the third larval instar. This was probably induced by some factor associated with lack of moisture in the sand, and appears to be broken (causing completion of development) by an effect of increased moisture content after heavy rain. This phenomenon probably does not occur in the anautogenous form.

Earlier studies of crop loss following insect attack on cotton in the elephant-grass zone of Uganda were followed up for two more seasons (1965–67), using large plots and routine spray schedules with different insecticides. The spray schedules were four or six fortnightly applications of insecticide, beginning at week 8 from emergence in the 1965–66 season, and four fortnightly or eight weekly sprays in the 1966–67 season. The insecticides used were DDT, endrin and dicrotophos in the first season and DDT, endrin and endosulfan in the second.

Estimates of Taylorilygus vosseleri (Popp.), Heliothis armigera (Hb.), Earias biplaga Wlk., Cryptophlebia leucotreta (Meyr.), Pectinophora gossypiella (Saund.), Dysdercus spp., Aphis gossypii Glov., Tetranychus sp. and Eotetranychus sp. showed that, although one or other of the insecticides reduced the different pests to very low levels, yield increases were not obtained. In the 1966–67 trial, when the more important pests were present in very low numbers, DDT and endosulfan significantly reduced yields of clean seed cotton and it is suggested that these formulations are slightly phytotoxic to Uganda cottons.

The relationship between the shedding of fruiting bodies and the harvesting of the crop showed that sprays applied after week 14 did not affect the total crop in any way. Increased soil fertility caused the plants to form more fruiting bodies and, although many of these were shed, a higher proportion were retained with or without protection from pest damage.

It is concluded that the pest damage is too light to affect yields of early-sown cotton where varieties of indefinite growth habit can compensate for early loss of fruiting bodies in the extended growing season. Routine spraying gives no benefit and, in some seasons, can be harmful.

Othreis materna (L.) is an important fruit-sucking moth in Rajasthan (India). The immature stages are described in detail and illustrated by means of photographs and setal maps, points distinguishing this species from O. fullonia (Cl.) being noted. Females laid 200–400 eggs; the durations of the egg, larval and pupal stages on Tinospora cordifolia were 3–4, 16–23 and 10–13 days, respectively.

The factors of resistance to many insecticides were located and isolated in a homozygous condition from the diazinon-selected SKA strain of house-flies (Musca domestica L.) by inbreeding each of the five autosomes of the SKA strain into a susceptible multi-marker strain ac;ar;bwb;ocra SRS. The insecticides were: DDT, methoxychlor, tri-butyl tin, the methoxy and ethoxy analogues of parathion, chlorthion and malathion and their corresponding phosphates, diazinon and diazoxon.

The SKA flies' autosomes had the following factors of resistance:—autosome I—very slight resistance to ethyl-chlorthion; autosome II—gene a for low ali-esterase activity which conferred weak to moderate resistance against all organophosphates tested, and Deh (DDT-dehydrochlorinase) which gave great resistance to DDT, but none against methoxychlor; autosome III—Pen, which delayed knock-down by slowing down the entry of insecticides into the flies and had a negligible effect at death except against tri-butyl tin and methoxychlor, and a factor of resistance to Zectran unaffected by sesamex; autosome IV—Dld, the major factor of resistance to dieldrin; and autosome V—Ses, a sesamex-suppressed factor, which gave weak to moderate resistance against ethyl-malaoxon, diazoxon, diazinon, DDT and methoxychlor, but was ineffective against the other organophosphates tested.

TBTP (S,S,S tri-butyl phosphorotrithioate), an ali-esterase inhibitor, greatly synergised organophosphates only against insects with gene a. Pretreatment with sesamex, an inhibitor of microsomal activity, elicited two types of response: antagonism with most of the thioates, most pronounced in flies with gene a, and synergism with the phosphates, especially evident with flies with factor Ses. The possible reasons for differences in the response to organophosphates after pretreatment with TBTP or sesamex, and the nature of the resistance factors are discussed. High resistance in SKA flies against organophosphates arises through the interaction of resistance factors which singly give only weak to moderate resistance.

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.