330 



Parasites developing in the egg include the two Myrmarids, Parana- 

 grus osborni and Anagrus frequens, the parasitism averaging about 

 50 per cent. The latter was introduced from Australia about 1904 

 to control Perkinsiella saccharicida, and has also been bred from the 

 eggs of a native species of sweet potato leaf-hopper. Paranagrus 

 osborni was introduced from the Philippine Islands in 1916 to control 

 the maize leaf-hopper. Usually one egg only is laid in the host-egg, 

 and this hatches within 24 hours. The larva grows until it nearly 

 fills the eggshell ; on the 6th day it pupates within the shell of the 

 egg it has consumed and 5 days later emerges as an adult. Males are 

 scarce in these species, a great deal of the reproduction being partheno- 

 genetic. The short life-cycle (11 to 12 days in summer at sea-level) is 

 the most important factor in the abundance of this parasite. 



Two species of Tetrastichine egg-parasites occur, viz. : — Ootetrasii- 

 chus beatus, and an undescribed species commonly known as the 

 Formosan Ootetrastichiis. The former was introduced from Fiji in 1905, 

 the latter from Formosa in 1916. The egg of 0. beatus hatches in from 

 2 to 3 days, pupation occurring about 9 days later and the adult 

 emerging in another 10 days. Males of this species have never been 

 seen, reproduction being entirely parthenogenetic. 



A Dryinid parasite, Haplogonatopus vitiensis, develops on the 

 nymphs of the leaf-hopper, the larva feeding on the fatty tissues of 

 the body. This parasitism is indicated externally by a small sac that 

 usually appears on the host-nymph behind the tegmina about 10 days 

 after oviposition. When mature, the larva emerges from the sac, 

 leaving the hopper to its fate, and pupates for a period of several 

 weeks. This parasite is too rare to be of great value and is abundantly 

 hyperparasitised. Pipunculid flies and Stylopid beetles also parasitise 

 P. maidis, although their effect has not been observed. Predaceous 

 enemies include an ant {Pheidolemegacephah), aCoccinellid {Coleophora 

 in&jualis), a bug {Zelus peregrinus), an earwig {Chelisoches morio) and 

 spiders. 



Brain (C. K.). A Preliminary Report on the Cotton Pests of South 

 Africa. — Union S. Africa Deft. Agric, Pretoria, Local Ser. no. 59, 

 26th August 1918, 29 pp., 24 figs. [Received 3rd June 1919.] 



There are many problems to be solved before the cotton-growing 

 industry can be established in South Africa on as large a scale as is 

 desirable. As the insect fauna of the country is exceptionally rich, 

 and as the flora comprises a large number of wild plants more or less 

 closely related to cotton, the question of insect pests is a most important 

 one, since it is highly probable that when cotton is grown to any extent, 

 pests will be discovered that are peculiarly South African. At present, 

 however, all the insect pests known to cotton growers are well known 

 in other parts of the world. Little study has been given to them in 

 South Africa, and the accounts given in this paper are taken from the 

 records of other cotton-growing countries. It is desirable to obtain 

 definite information for South African conditions, and much of this 

 could be supplied by cotton growers. Remedial measures practised 

 in other countries may not be suitable in South Africa, but the remedies 

 generally recommended are given for reference and trial. Two of the 

 most serious cotton pests, the boll- weevil [Anthonomus grandis] and the 



