An investigation was carried out into the use of water traps for sampling Glossina morsitans submorsitans Newst. and G. tachinoides Westw. in Yankari Game Reserve in sub-Sudan savanna in northern Nigeria. The traps consisted of coloured trays filled with water plus small quantities of formalin and detergent. Colour was thought to be the major factor attracting flies to the traps, white traps being most effective for G. m. submorsitans and black ones for G. tachinoides. Water traps were compared with biconical traps, and both methods showed similar changes in catches in different vegetation types over a year. Males and females of both species showed a marked expansion in distribution in the rains and a contraction to riverine woodland in the dry season, though females of G. m. submorsitans could be caught in the adverse deciduous woodland and open savanna all year round. Water traps are considered a very cheap and practicable sampling method for ecological studies on these species of Glossina, providing specimens well preserved upon capture for later morphometric and analytical studies.

Chromolaena odorata is a tropical American species of the Compositae that has become a serious problem in plantations in the tropics of Asia and Africa. The history of attempts to control it using the arctiid moth Pareuchaetes pseudoinsulata Rego Barros (misidentified in previous literature as Ammalo insulata (Wlk.)) is summarised. The taxonomy and distributions of the five species in Pareuchaetes are presented, together with keys based on genitalic characters, three new synonyms and one new combination. Information on the biogeography and ecology of the Pareuchaetes species is used to assess their potential as biological control agents.

Ollarianus balli (Van D.), a leafhopper vector of disease-associated mycoplasma-like organisms, was found to be rare in Jamaica. Its distribution and frequency were governed primarily by the distribution and density of its specific field host, the wild legume Rhynchosia minima on which it completes its life-cycle. Under suitable temperature conditions, O. balli was easily reared in captivity on R. minima and pigeon pea (Cajanus cajan), although the latter is not a natural host. It oviposited into the hypodermal tissues covering veins of sterns, petioles and the abaxial surfaces of older leaves. Eggs hatched 10–15 days after oviposition and there were five nymphal instars. Instar 1 was distinct from instars 2–5 which, except for size, were similar in appearance. The first adults matured some three weeks after the final moult. There appeared to be little difference in the average life-span of males and females of O. balli.

Data from surveys in 1951, 1972, 1973 and 1978–79 showed that tick numbers are generally low on the miniature breed of cattle in the Yemen Arab Republic and tick-borne diseases have not been recognised as a serious problem. This breed should be investigated for properties of resistance to tick bite. Each tick species commonly infesting livestock has been recorded as transmitting viruses (and some also rickettsiae) causing human illness in Africa and/or Eurasia. Between 1300 and 2000 m in altitude, Amblyomma variegatum (F.) is more abundant on camels than on cattle and Boophilus annulatus (Say) infests cattle. Below 1500 m, B. kohlsi Hoogst. & Kaiser is more abundant on goats than on sheep. Haemaphysails sulcata C. & F. infests sheep in certain highland areas. Hyalomma dromedarii Koch is the most prevalent and abundant tick of livestock. H. anatolicum excavatum Koch is next in abundance on camels. The numbers of H. anatolicum anatolicum Koch vary greatly in collections from different years. Few examples of H. erythraeum Tonelli-Rondelli were taken. H. impeltatum Schultze & Schlottke and H. marginatum rufipes Koch are widely distributed; the former is most abundant in coastal lowlands, the latter in humid habitats. H. arabica Pegram, Hoogst. & Wassef is recorded from goats, and also sheep, in southern hills. Immature examples of Hyalomma spp. are especially abundant on camels and hares. Rhipicephalus evertsi evertsi Neum. is common in the highlands, as is R. simus Koch below 2000 m. Species of the R. sanguineus (Latr.) group occur on some livestock.

Adults of a field strain of Blattella germanica (L.) resistant to dieldrin and bendiocarb were used to evaluate two insecticide bait formulations, 50% boric acid plus 50% porridge oats and 0·25% iodofenphos gel in comparison with gel alone and culture food. All cockroaches from the boric acid plus oats treatment died in less than 20 days, whereas some that fed on iodofenphos gel, culture food or gel blank survived for 30 days. Both insecticides caused females to drop their oothecae prematurely, and fewer eggs from the boric acid plus oats treatments hatched. More cockroaches exposed to boric acid plus oats bait died outside the harbourages than those from the iodofenphos gel treatments. Boric acid plus oats or iodofenphos gel offered together with culture food were eaten throughout the treatments. With iodofenphos gel alone, no bait was eaten after four days, but mortality continued for 21 days. The minimum amount of insecticide bait required to kill all 100 cockroaches was about 1340 mg iodofenphos gel, and 100·0 mg boric acid plus oats. After exposure for 24 h, all cockroaches died within nine days after exposure to boric acid plus oats, whereas with iodofenphos gel some survived after 21 days. Two further applications of gel bait in the iodofenphos experiments on days 13 and 17 failed to increase mortality although some bait was eaten. B. germanica was killed more quickly by both insecticide baits when deprived of drinking water.

Field experiments conducted on cotton in southern Sri Lanka, where the main pests were Heliothis armigera (Hb.), Earias vittella (F.) and Pectinophora gossypiella (Saund.), indicated that a damage action threshold of five squares and six bolls per 30 plants could be used for forecasting and early warning in pest management. A parallel sampling study indicated that a sample size of 30 plants would reduce the sampling error to acceptable levels as well as being a more convenient number in the field. An expression that corrects experimentally established thresholds for changes in the cost of control and the market price of the yield is given.

The productivity of adults of Trogoderma granarium Everts was reduced following fumigation of the larvae with high dosages of carbon tetrachloride, ethylene dibromide or phosphine. Carbon dioxide, ethylene oxide, methyl bromide, methyl iodide and trichloroethylene had little influence on the productivity. From 0 to 23 % of surviving larvae diapaused compared with 3 % of untreated ones.

Locomotor activity in an actograph and oriented locomotor movements in an olfactometer were recorded for fifth-instar nymphs of Rhodnius prolixus Stål exposed to test stimuli expected to elicit food-seeking behaviour. A natural food source (hamster or human forearm) proved to be the most attractive stimulus. Warmth alone was least stimulating for long-range orientation. As with mosquitoes, carbondioxide and moisture proved to be attractive, as well as the odour of a hamster. Lactic acid did not seem to play an important role in orientation. Activation by the different stimuli was most pronounced during the scotophase of the circadian cycle. Circadian activity ran-free for two weeks in constant darkness. The results indicate that the stimuli that elicit locomotor activity in the actograph are in some way implicated in the switching of the taxis mechanisms that utilise the airstream for orientation.

Development rates of engorged examples of Ixodes ricinus (L.) and the onset and duration of questing activity of unfed ticks were investigated in gauze cages in the field in the Irish Republic. Development rates of the various stages were broadly similar to those described in other studies but differed in small detail from most of them. It was found that larvae that fed during or after the first two weeks of August entered diapause. The activity periods of questing ticks were found to agree closely with observations made in the field, and the origins of the various peaks in tick activity in the field were thus elucidated. It was established that considerable interchange between autumn-feeding and spring-feeding populations of ticks can occur, and it is concluded that the extent of this is largely controlled by the weather, being accentuated by high summer temperatures.

Activity in virgin and pregnant females of Glossina morsitans morsitans Westw. was very low and mostly took the form of short bursts of flight. Recently-fed virgins and females in early and mid-pregnancy were least active. In late pregnancy, activity increased and more walking occurred. In all classes of females, activity was least around midday, but the V-shaped curve became less pronounced as parturition approached. There was evidence of a slight preference for black over white surfaces when landing but a clear preference for black resting sites. Virgin females preferred to alight and rest on vertical surfaces at the borders of areas of visual contrast; pregnant females preferred to alight and rest on horizontal surfaces and showed no attraction to regions of contrast. In a horizontal light gradient, pregnant females selected lighter resting sites as the day progressed. In late pregnancy, there was an increasing tendency to rest in darker sites. Increasing the temperature in the light gradient caused an increase in activity around 34°C and a switch to photonegative behaviour. After larviposition, the females became strongly photopositive even at high temperature (38°C), but after a feed they reverted to the ‘normal’ photonegative response to high temperature.

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 life-span and fecundity of females of Spodoptera littoralis (Boisd.) of strains that originated from Crete and Egypt were studied in relation to delays in mating. Virgin females and those that were not mated until eight days from emergence lived longest (means of 17 and 18 days, respectively). Earlier matings progressively reduced life-span; those mated at 0 or 1 day lived for averages of only 7·5 to 10·5 days. Preoviposition periods were extended when mating was delayed, from averages of 2 and 3 days, to averages of 9 and 10 days. Both the number of eggs laid and the percentage hatching were reduced by delays in mating beyond a critical period. In the Cretan stock this critical period was two days, but in the Egyptian stock it was less than a day. Cretan females mated early in life laid, on average, 726 eggs each and produced 541 caterpillars. When mating was delayed for four and six days, only 303 eggs were laid per female and only 93 caterpillars hatched. In the Egyptian stock females mated within one day of emergence laid 1208 eggs each and produced 948 caterpillars, compared with 499 eggs and 199 caterpillars for those not mated until six or eight days after emergence. Since a two-day delay in mating reduced the number of caterpillars to between one-fifth and one-tenth of those that resulted from early matings, it would appear that a smaller caterpillar population would result from control methods that reduced the availability of males, either by mass-trapping or blanket-spraying crops with pheromone.

The flight performance of Simulium ornatum Mg. s.l. was measured under laboratory conditions using a simple flight mill. Males and unmated females were flown and the duration, distance and average speed of flight were recorded for adults fed on water only, sucrose, blood & water, or blood & sucrose. On 91% of all test occasions sucrose-fed insects flew but 25% of those on water only did not fly. Feeding flies on 10% sucrose solution markedly improved both willingness to fly and flight performance, and under these conditions maximum duration, distance and average speed recorded were 4.9 h, 4·2 km and 2·84 km/h, respectively. The ratio of average to maximum speed was 0·631 for females and 0·610 for males, with absolute maximum speeds of 3·19 and 2·99 km/h, respectively. Duration and distance flown were well-correlated, speed being the least variable aspect of flight performance measured. The distributions of flight duration and distance flown were skewed such that few insects made long flights. Mean flight performance at different ages was measured; unmated females appeared to retain a high level of willingness to fly throughout the age-range tested (up to 33 days). The longest recorded flight (5·3 h) was made by a female during an overnight experiment. The implications for long-range flight movements by simuliids are discussed.

In the presence of the odour of carbon dioxide and acetone, an electrified net adjacent to a stationary cylindrical black model in the Zambezi Valley, Zimbabwe, in the hot dry season caught more adults of Glossina morsitans morsitans Westw. and G. pallidipes Aust. than in the absence of odour. In the absence of odour, a moving model attracted more G. m. morsitans males than did a stationary model. Between 20 and 50% of males of G. m. morsitans but only 0 to 12% of males of G. pallidipes near a model were caught by electrified decoys (surrogate females) on the model. Hidden observers recorded the numbers of flies copulating with decoys baited with pheromone or pheromone plus bisazir (P, P-bis(1-aziridinyl)-N-methylphosphinothioic amide) on a stationary model with odour between 16.00 and 19.00 h daily. Males of G. m. morsitans contacted the decoys with much greater frequency than did males of G. pallidipes although the latter species was the more abundant. The numbers of copulatory attempts by G. m. morsitans males during each 10 min suggested that changes were a function of the total numbers of flies attracted to the model. At all times of the day, the average duration of copulation was 37–40 s. However, approximately 50% of responses were of 10 s duration or less and fewer than 10% endured for longer than 3 min. The presence of bisazir on the decoys did not influence the response duration or the total numbers of flies responding. A comparison with laboratory data suggested that further refinement of technique will allow pheromone-baited decoys to be used in the autosterilisation of G. m. morsitans males with bisazir in the field.

Surveys of parasites of Sylepta derogata (F.) on cotton at Ibadan, Nigeria, in 1979–80 showed that there were three larval parasites: Apanteles syleptae Ferrière, A. sagax Wlkn. and Charops sp. An average of 17·7% parasitism was recorded, and A. syleptae accounted for 98·6% of this. There were three pupal parasites: the chalcidid Brachymeria feae Masi, the ichneumonid Xanthopimpla sp. and the tachinid Cadurcia auratocauda (Curr.). Together, they caused an average of 31·7% parasitism. Xanthopimpla was the most abundant, while B. feae was of secondary importance.

Three West African strains of Anopheles gambiae Giles were intensively selected for DDT resistance at the adult stage using both mass selection and family selection with inbreeding. The LT50s for 4% DDT were thereby raised to 2–6 h, i.e. 6–18 × that of a susceptible strain. The selected strains were found to show DDT resistance as first-instar larvae and permethrin resistance as adults. The results of tests for the number of genes involved in causing the resistance and their linkage to genes for dieldrin resistance were equivocal. One of the DDT-resistant strains was bred in population cages with overlapping generations. Releases were made of males of the R70 translocation strain which transmit DDT and dieldrin susceptibility to their female progeny. When DDT selection on the cage population was relaxed, the releases caused a more rapid and complete loss of resistance than occurred in a control population. When selection for DDT resistance was applied to females of the cage population, the releases were able to prevent a build-up of resistance. The use of male releases is discussed as a possible means of countering insecticide resistance in mosquitoes.