84 



Mally (C. W .). Some Zoological Factors in the Economic Development 



of South Africa.-- .S". African Jl. Sci., Johannesburg, .wii, no. 1, 

 November 1920, pp. 64-75, 1 plate. 



Insect pests of maize are responsible for the loss of about 25 per cent, 

 of the crop in South Africa. They include the stalk borer \ Biisseola 

 ftisca], cutworms, HcUothis [Chloridea) ohsoleia (ear worm), Hctcrony- 

 chus arator and a weevil, Strophosonnts amplicollis. The loss is \-alued 

 at £1,350,000 annuallv, B. fiisca alone being responsible for some 

 £540,000. 



Wheat pests include Toxoptera graminum (wheat aphis), which is of 

 the greatest importance ; a Coccinellid, Epilachna similis, which 

 becomes at times a serious pest in the Eastern Province ; and in the 

 Western Province certain bugs, particularly Blissiis diplopfcrits, Dist. 



Olives are grown under extremely favourable conditions and would 

 produce a very valuable croj:) if it were not for the depredations of the 

 Tingid, Teleonemia australis, Dist., and the Chrysomelid, Pscitdococ- 

 cinella sexvittata, Che\'r. When it has been demonstrated that these 

 pests can be controlled by spraying and fumigation, it is hoped that 

 the cultivation of olives will greatly increase. 



Certain insects are always present, such as Pseudococciis spp. (mealy- 

 bugs) on vines, bagworms on wattle, and termites. Others that are less 

 uniformly abundant include Cirphis (Leticania) unipuncta (American 

 army worm) and LapJiygma exempta (South African mystery worm). 

 The extreme fluctuations in the numbers of these moths are not suffi- 

 ciently understood ; natural enemies, climatic conditions and variations 

 in farm practice may all be factors influencing their abundance ; 

 knowledge of the causes of fluctuation might provide a clue to successful 

 remedial measures. 



Some of the remedial measures that have turned failure into success 

 in South African cultivation are briefly reviewed. Phylloxera threatened 

 the grape industry with extinction until a resistant stock was discovered ; 

 the Australian scale [Icerya pnrchasi] was ruining Citrus and other 

 crops until its natural enemy, Novius cardinalis, was introduced. Peach 

 trees were smothered with the scale, Aiilacaspis (Diaspis) pentagona, 

 and plum trees with the mite, Bryobia sp., until sprays of lime-sulphur 

 and salt saved the trees. Fumigation has been revolutionised by the 

 application of the principle of reducing hydrocyanic acid gas to liquid 

 form by cooling. Many other problems still await solution, and the 

 need is urged for making every possible provision in the form of 

 endowment for educational institutions, so that the liighest possible 

 efliciency may be secured in training those who show ability. 



Martin (J. F.), Stexe (A. E.) & Sheals (R. A.). How to distinguish 

 and combat the White Pine Blister Rust. — Rhode Island State 

 Bd. Agric, Entom. Dept., Kingston, BuU. N.S. no. 1, Februar\- 1920, 

 38 pp., 13 plates. [Received 21st December 1920.] 



Insect injury to white pines [Pinus strobus] has often been mistaken 

 for blister rust. The life-histories of the insects involved are here 

 briefly discussed, and remedial measures advocated. They include : — 

 .the white pine weevil [Pissodes strobi]; the pine bark Aphid [C/iermes 

 pinicorticis] ; the European pine-shoot moth [Rhyacionia biioliana] and 

 the European pine sawfly [Diprion similis]. The work of a bark- 

 miner, probably Marmara sp., is also often confused with blister rust 

 infection. Trees weakened by the disease are generally attacked by 

 bark-beetles. 



