Two sprays of Abate or Delnav for the control of Scirtothrips aurantii Faure on citrus trees were shown to cause heavy infestations of Aonidiella aurantii (Mask.) in orchards already under integrated control. Some of the control plots appeared to be affected by the surrounding treatments. An additional three sprays proved conclusively that Abate and Delnav could seriously disrupt the biological control of red scale. The effects of Abate were generally two or more times as severe as those caused by Delnav, while Abate caused a correspondingly greater reduction of parasitism of red scale by Aphytis africanus Quednau.
The ticks were tested at intervals, until after the onset of oviposition, in choice chambers providing two humidities. Between tests they were kept at 100, 33, or 0 % R.H. In chambers offering 100/33 % R.H. the ticks initially showed dry-preference; from three days after collection until the sixth (last) day those kept at high humidity and 25ï¿½C showed wet-preference, those kept at the lower humidities also showed wet-preference except on the fifth day.
Delayed emergence up to two years is recorded. The ichneumonid parasitizes larvae of Mesocelis montana Cramer. The Ichneumon Zonocryptus xanthomerus Brullï¿½ is a parasite of the larva of Mesocelis montana Cramer (Lepidoptera: Lasiocampidae), which is a serious pest of mesembryanthemums in parts of Namaqualand (Waiters, Waiters & Lourens, 1971). The Ichneumon larvae leave the parasitized caterpillar just before the latter pupates in spring and then spin light brown silken cocoons within the cocoon already constructed by the caterpillar, the tough cocoon of the latter affording additional protection to the diapausing parasite. Up to ten parasites per caterpillar have been recorded.
New localities are recorded for Bittacus walkeri Esben-Petersen in South Africa, B. weelei E.-P. in Zambia, and B. fumosus E.-P. in Tanzania. Through the courtesy of Dr. E. Pinhey, I have had the opportunity of examining some Mecoptera from the National Museum, Rhodesia. Unfortunately, the abdomens of some specimens are incomplete and some of the label data is indistinct but the records are, nevertheless, of interest. Three species are included and all represent extensions of the known ranges of the species.
Culex theileri Theobald. Previous attempts to colonize this mosquito were unsuccessful owing to the absence of mating. However, mating occurred when a special artificial lighting arrangement giving simulated dawn, day and dusk periods was used (Jupp & Brown, 1967). The methods used to establish and maintain the colony were similar to those previously descriptionbed for Culex univittatus (Jupp & Brown, 1967), except that the initial use of a ""walk-in"" cage was unnecessary. Starting material was a collection of gravid females from Lake Chrissie in the eastern Transvaal highve1d from which egg rafts were obtained.