Through the years I have worked on entomology, I have been struck more and more by the apparent lack of interest among South Africans in systematics. I am myself a systematist and I hope I shall be forgiven by the devout band of systematists who are born and bred South Africans, for this statement, especially after they have given the matter serious thought.
Opisthophthalmus carinatus Peters and O. wahlbergi Thorell are common in South West Africa and Botswana, and it is thus not surprising that they should also be found just north of the Zoutpansberg in the northern Transvaal. The Albany Museum records O. carinatus histrio Thorell from Fleshfontein in the northern Transvaal. This locality is presumably Vleeschfontein on the farm Kalkfontein 115 in the north-western Transvaal. O. carinatus histrio is very near to the typical form, the main difference being a slightly greater pectinal tooth number and the absence of transverse grooves on the last sternite in the males.
The sixth instar larvae which constitute the bulk of a colony of the harvester termite, Hodotermes mossambicus (Hagen), performed most of the duties in the nest. They groomed and fed the adult workers, small larvae, soldiers and reproductives and also attended to the eggs. They were probably responsible for the distribution of social pheromones through the colony. Isolating the different castes and stages from the colony, enhanced their attractiveness to the large larvae.
In 1873 Gerstaecker descriptionbed two new species of Centrotus Fabricius, and for years it was thought that the types of these species, fenestratus and pacificus, had been lost. Fortunately they have recently been located in the Humboldt University Museum, East Berlin, and Dr U. Gï¿½llner-Scheiding has very kindly loaned them for study. They arrived just in time for me to comment on them and give their new combinations in a brief addendum to my paper on the African Centrotinae (Capener, 1968). It is considered desirable to present redescriptionptions and figures of both species.
Mites of the family Nanorchestidae have a worldwide distribution for they are known to occur in European, North American and Antarctic soils. Recent soil ecological studies in South Africa have shown that they form a numerically important part of the local soil-inhabiting Acari. Olivier & Ryke (1965) and Loots & Ryke (1966) reported the family Nanorchestidae as occurring in large numbers in soil covered by kikuyu grass (Pennisetum clandestinum) and in different types of pasture soil respectively. These authors made observations on the populations of species of this family over a period of one year.
In a previous article (Van den Berg, 1968) attention was given to the male genitalia of a few type-species of the Notodontidae. Earlier work on the Notodontidae emphasized mainly the male genitalia. The female genitalia offer useful characters for identification, and the aim of this study was to provide a key based on these characters for separation of the type-species of the genera occurring in South Africa.
A previous paper (Robertson 1967) dealt with field records for Saltatorial Orthoptera and contained details of records made, plant species and collecting localities. The present paper includes similar records for the Dictyoptera. During the period when the field data were collected a Robinson type mercury vapour light trap using a 125 watt 220 volt bulb was in use at Ukiriguru, the main agricultural research centre for the area, 17 miles south of Mwanza.
In southern Africa, the family Entomobryidae appears to be by far the most well represented family of the Collembola, in the number of both species and individuals. The new monotypical genus descriptionbed here differs from other entomobryid genera in that its representatives bear striking adornments on the first and second segments of the antennae. In this, the genus resembles Lepidoregia Delamare-Deboutteville, 1948, which has 9 strong ciliate setae arranged transversely around the base of the second segment of the antenna. However, the differentiated setae in the new genus are more numerous, are of several different types and are carried on the first two segments of each antenna. The type-species has so far been found only in the Eastern Transvaal Lowveld and Moï¿½ambique.
A preliminary study was made of the four main Culex species which occur near Johannesburg in the highveld region of South Africa to determine in which developmental stage they overwinter. This was undertaken because some of these species are vectors or potential vectors of Sindbis and West Nile viruses and might constitute an overwintering mechanism for the viruses.
Some South African representatives of the genus Galumna Von Heyden, 1826 are descriptionbed, viz. Galumna rostrata spec. nov., Galumna dimidiata spec. nov., Galumna tricuspidata spec. nov., Galumna capensis capensis subspec. nov. and Galumna capensis dissimilis subspec. nov. Only one known galumnid, Galumna discifera Balogh, 1960, is represented in the material investigated.
A crash in a population of Hodotermes mossambicus (Hagen) was observed after a prolonged drought during 1966. Virtually no recovery in numbers has taken place since that time. The crash was probably caused by lack of moisture and/or food although the possible effect of natural enemies was not investigated and therefore could not be ruled out entirely. The quantity of food carried underground by the termites as well as counts of the number of foraging holes and soil dumps were taken as indices of the size of the population. About one ton of dry plant material per morgen was produced on the study area per year. Differences in food production could not be held responsible for the population changes of the termites.
A steam volatile oil isolated from Chrysocoma tenuifolia (Berg) (bitterbos or bitterkarroo) has both contact and vapour toxicity to the harvester termite Hodotermes mossambicus (Hagen). The oil also has a strong repellent action.
The shrub Pride of Barbados, Caesalpinia pulcherrima (L). Sw., which is used in the Eastern Transvaal for hedges was found to be heavily infested with the citrus thrips, Scirtothrips aurantii Faure. A method is descriptionbed for using these populations to screen insecticide sprays. At a concentration of 0.075% active ingredient the insecticides Carbicron 50% EC [3-(dimethoxyphosphinyloxy)-N,N-dimethylciscrotonamide], Delnav 50% EC [2,3-p-dioxanedithiol S,S-bis (O,O-diethylphosphoro dithioate)], and Banol 75% WP [6-Chloro-3,4-xylyl methylcarbamate] yielded results which were equal to or better than those obtained with parathion 25% WP [Diethylparanitrophenyl thiophosphate] which is used commercially to protect citrus crops from thrips attack.
The effect of light, humidity and temperature on the behaviour of Dacus ciliatus was investigated and a study was made of the specific preference shown by the insect in gradients of light, humidity and temperature respectively. The mature larvae are photo-negative on leaving the fruit while the adult flies are photo-positive. The smaller the differences in light intensity between two halves of a long, narrow cage, the smaller is the response of the adults. Adult flies exhibit no definite hygroreaction but their temperature preferendum lies between 25 and 355 C (av. 29.55C)