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Synopsis An account is given of the monthly fluctuations in size of catch of mosquitoes biting man on a sugar estate in Jamaica. These catches are compared with others made in donkey-baited and chicken-baited traps in the same area.

Interviews identified that most small-scale maize farmers in central Uganda and in the Southern Highlands of Tanzania plant home-saved seed of landraces or seed derived from various open-pollinated and hybrid varieties. Some farmers also bought a portion of their seed, either certified seed, locally traded seed or even maize sold for consumption. Selection for home-saved seed was generally among harvested cobs. Big cobs with many, regularly arranged, large, white, flint kernels were preferred. A maize cob may bear several hundred seeds, so a farmer needs to save

SUMMARY Intercrops of bean and finger millet were tested as a possible means of controlling maize streak virus disease (MSVD) in maize by disrupting the mating behaviour of the insect vectors of the maize streak virus, Cicadulina mbila and C. storeyi. A series of three trials were done. In the first, MSVD incidence 2 months after sowing was reduced to 14.9% and 17.4% in millet and bean intercrops compared to 29.5% in the pure maize stand. The number of male Cicadulina spp. caught on sticky pole traps was also significantly reduced relative to the control, but there was little effect on the catch of females. There was no significant yield penalty for the millet intercrop but maize yield was 49% lower in the bean intercrop treatment than in the pure stand. In the second trial, there were two millet and two bean intercrop treatments and a maize only control. Fewer male Cicadulina spp. were caught in the intercrop treatments relative to the control but MSVD incidence was reduced in one millet intercrop treatment only for which the associated maize yield penalty was 89%. In the final trial the bean intercrop was again tested but it had no effect on MSVD incidence. These experiments demonstrated that intercropping maize with bean or millet decreased vector activity and/or vector numbers. Vector catches were predominantly male, and catches of males but not females were reduced in the intercrop treatments compared with pure stands. However the lower vector catch was not consistently associated with a significant reduction in MSVD incidence, and when it was there was often an associated yield penalty in the maize due to the intercrop.

The survival experience of 46,000 Veterans Administration (VA) male cancer patients was analyzed and compared with the results of three other studies. In the VA data, no significant differences were found between white and black patient cancer survival rates except for bladder cancer; this observation differs from those in other studies. In the VA, all patients receive the same treatment with no distinctions whereas most U. S. hospitals place their patients into categories based on ability to pay. This factor probably accounts for the lack of racial differences in survival rates in the VA and the existence of racial or socioeconomic differences in survival rates in the other studies.

Two sequential charts designed by I. BROSS, used to analyze serial data for two treatment groups, are studied in this paper. Simulation techniques, rather than theoretical calculations, have been used to determine more complete characteristics of these designs. Of particular interest are the estimates of percentiles of the distribution function of “sample size required to reach a statistical decision”. The distribution parameters of the one-sided tests, not studied by BROSS, are also given. Es werden 2 sequentielle Plane von I. BROSS untersucht, die zur Analyse von seriellen Daten fur 2 Behandlungsgruppen verwendet werden konnen. Um diese Plane umfassender zu charakterisieren, wurde die Simulationstechnik eingesetzt. Von besonderem Interesse waren Abschatzungen von Perzentilen der Verteilungsfunktion der “erforderlichen Stichprobengrose, um eine statistische Entscheidung zu treffen”. Es werden Verteilungsparameter von einseitigen Tests angegeben.

1. Long-term changes in the numbers of Zonocerus at oviposition sites reflect changes in the maturity of the general population. 2. Short-term changes in the numbers of Zonocerus at oviposition sites are associated partly with normal diurnal behaviour in which roosting occurs at night. 3. Immigration of Zonucems, particularly females, into the oviposition site occurs prior to periods of oviposition activity. Emigration follows oviposition. 4. The majority of Zonocerus move upwind into the oviposition site suggesting an odour and/or sound attraction. 5. Periods of intense oviposition activity follow heavy rainfall.

1. About 166,000 African armyworm moths, Spodoptera exempta (Walk.), were marked at an emergence site near Nairobi when they fed at night on trees baited with dyed molasses. 2. Six marked moths were captured in pheromone traps, including one at 90 km after flying for only one night, and another at 147 km. 3. Moth flight trajectories deduced from radar and from marking showed that migration was downwind. 4. During migration, moths become dispersed; hence the high densities that lead to outbreaks must be produced by concentration. 5. Some moths were ready to mate on the same night they completed their long-distance flight.

1. The dry-season population of Zonocerus in southern Nigeria oviposits in dense aggregations under single or clumped woody plants or on the edge of tall continuous stands of vegetation. No egg pods were found oviposited singly. 2. The vegetation under which oviposition occurs is the most common available at the time of the year. There seems to be no selection of particular species of plants so long as they provide good low shade. 3. Oviposition can take place in a wide range of gravelly soils. 4. Topography is not important as long as the oviposition site is on high ground away from damp areas subject to flooding. 5. There was a mean of 618 pods per oviposition site from forty-one sites which were dug up, and there was a significant correlation between the area of a site and the number of pods. 6. There was a marked tendency for oviposition sites to be found close to cassava. At two localities of approximately 20 ha each 90% of the sites were found within 30 m of cassava. 7. It is suggested that permanent shade is the most important factor in the selection of a site and this is probably related to the survival of the eggs during their 6–7 months development.

1. Onset and spread of the severe outbreaks of African armyworm, Spodoptera exempta (Walk.), over Ethiopa, Kenya, Tanzania and Burundi in late 1984 have been analysed in relation to trap and weather records. 2. Although first outbreaks in each country appeared progressively further south, winds on the best estimated dates of moth concentration and egg laying blew from directions precluding moth movements between them. 3. Such independently developing outbreaks are called ‘primary’ to distinguish them from any ‘secondary’ outbreaks that may develop from them. 4. Parent moths giving rise to all seven areas of primary outbreaks were derived from low-density populations that had persisted through the dry season, probably near the coast of East Africa. 5. Primary outbreaks developed on the south-eastern sides of individual rainstorms over the highlands, most likely because windborne moths were concentrated there by convergent winds. 6. Of the secondary outbreaks within Kenya, Tanzania and Burundi, most were derived from only one area of primary outbreaks in Kenya, which were therefore critical for effective control of spread; the paucity of other secondaries was presumably due to a lack of timely rainstorms or other concentrating mechanisms.