In this paper six species of Marietta Motschulsky, 1863 are added to the two which are at present known from South Africa. Five of these are descriptionbed as new species from material reared from coccoid-infested plant material collected in South Africa. The sixth is a species originally descriptionbed from Madagascar and since recorded from West Africa. A descriptionption is also given of an apparently new species of Centrodora Foerster, 1878-the second from South Africa. This is a species of some value to forestry, for it was submitted for determination as a parasite of the eggs of a cicadellid pest of young wattle trees in Natal.
Tetrastichus ceroplastae is the most abundant parasite of Ceroplastes floridensis in Israel, where it also attacks C. rusci (L.). The egg, the three larval stages, prepupa, and pupa are descriptionbed, with observations on rearing methods, duration of development, mating, oviposition, fecundity and feeding of adults, and on the effects of host size on sex ratio, of temperature and humidity on survival, and of different sources of honeydew on longevity. Only the third ins tar larva and preovipositing female of C. floridensis and C. rusci were attacked. In some females the parasite egg was encapsulated and its development inhibited or prevented. Morphological changes in a parasitized scale are descriptionbed.
The species of the genus Synchortus Sharp (subfamily Noterinae) occur only on the continent of Africa and in Madagascar. The Madagascar species are not discussed in this paper. Eight species have been named from Africa: S. imbricatus (Klug), S. aequatorius Guign., S. simplex Shp ( aciculatus Shp), S. sparsus Shp, S. desaegeri Gschw. (= Hydrocoptus rhipax Guign.), S. abditus Guign., S. leleupi Guign. and S. dabbeni Rï¿½g. The latter has not been recognised since it was first descriptionbed and, as the unique type can not now be found, the accuracy of the descriptionption and the specific status of the type can not be checked.
A new species, Cerceris bambesae, is descriptionbed from the Congo, and a new subspecies of C. kalaharica Bischoff, namely, ovambo, from South West Africa. Redescriptionptions and figures are given of eight known species including four in which the male sex was hitherto undescriptionbed. Two homonyms, C. turneri Arnold and C. ponderosa Arnold, are recorded, the former renamed ventripilosa, the latter placed in synonymy with C. flavofemorata Arnold. The types of five known north African Palaearctic Cerceris species are briefly dealt with, of which C. schmiedeknechti Kohl is placed in synonymy with C. specularis Costa.
In laboratory feeding trials, the predacious mite, Amblyseius (Typhlodromalus) addoensis, fed only on the immature and adult stages of the citrus red mite, Panonychus citri. However, all stages of the red spider mite, Tetranychus telarius (L.), including the egg stage, were eaten by A. addoensis. Under field conditions, A. addoensis was found to be an effective predator of the citrus red mite. The variation in the numbers of P. citri observed on individual trees within an orchard could be explained by the variation in the numbers of predator mite on each tree. It is suggested that there is a critical ratio of about 3:1 between the numbers of active stages of P. citri and those of adult A. addoensis. If this ratio is exceeded then large populations of P. citri can be expected to develop.
The relative biting prevalence of mosquito species in the canopy and at ground level was studied in a gallery forest where monkeys had probably been infected with chikungunya virus in the canopy. Several species, some of which fed readily on monkeys, were observed to feed in significant numbers in the canopy. Considering prevalence, host preferences, arboreal tendencies, and vector capability in species where this is known, it is concluded that Aedes (Diceromyia) furcifer (Edwards) and/or Aedes (Diceromyia) taylori Edwards and Mansonia (Mansonioides) africana (Theobald) seem most likely to have been involved as vectors.
Measurements are presented which reveal that the soldier caste of Odontotermes okahandjae Fuller is dimorphic, not trimorphic as postulated by Fuller. This situation is compared with that in other species of Odontotermes, where a dimorphic soldier caste is rather exceptional, and in the related genus Macrotermes, where the soldier caste (always dimorphic) has minor soldiers which are less variable than these of O. okahandjae.
The type of Anchon nodicornis (Germar) is discussed, redescriptionbed and figured. A redescriptionption and figures of A. gunni Funkhouser is presented, and the following new species are descriptionbed and figured: A. dukei, A. tribulis, A. rusticanum, A. agnatum and A. cornulatum.
The two distantly related harvester termites Trinervitermes trinervoides (Sjï¿½stedt) (Termitidae) and Hodotermes mossambicus (Hagen) (Hodotermitidae) are common in the arid regions of South Africa. The swarming flights of both species occur in the summer shortly after the first substantial rains.
The solar and ultraviolet (2537 Aï¿½) radiation tolerances of castes of several termite species were determined. The most radiation tolerant workers were those which normally forage in the open, and furthermore they were the most darkly pigmented. Workers which do not normally forage in the open contained little cuticular pigmentation and showed low radiation tolerances. The larvae of all the species examined were pale and translucent in appearance and they were the least resistant. The soldiers which seldom venture out on the soil surface (with the exception of T. trinervoides soldiers) showed a surprisingly high tolerance. This is, may be incidental to the greater degree of sclerotization of the head capsule.
Redescriptionptions are given of Bittacus pobeguini (Navas) from east and west African material, and of B. moschinus Navas from central and east African material. B. kongoloensis Lestage is synonymized with B. pobeguini.
Experimental fumigation of citrus with ethylene dibromide (EDB) for two hours at a dosage rate of up to 20 mg/litre, was found to be inadequate for a complete kill of all stages of the false codling moth. For this reason, combinations of EDB fumigation and cold storage were tested, resulting in the development of a successful schedule consisting of a 2-hour fumigation with EDB at 16 mg/litre followed by cold storage for 18 days at 4,4 ï¿½ 0,5ï¿½C.
Two new species (Zygina viridis and Kybos theroni) are descriptionbed, the male of Zygina elegia (Cogan), previously known only from the females, is descriptionbed, and a male of Zygina purpureatincta (Cogan), previously descriptionbed as a female, is redescriptionbed and designated as lectotype; the last two species have been transferred from the genus Erythroneura.
Some coccinellids lay their eggs singly near their prey and the resulting larvae disperse from the oviposition site shortly after hatching. Other species, notably those that hatch from eggs laid in batches, postpone departure from the oviposition site and remain clustered together for a relatively long time on the empty egg batch before dispersing (Hagen, 1962). This latter type of behaviour favours sibling cannibalism while the larvae are clustered together on the egg batch. It is generally believed that such feeding benefits survival of the remaining individuals enabling them to make a more prolonged search for aphid food (Banks, 1956; Dixon, 1959).