172 



insects feeding on both species, while they may hitherto have been 

 merely of secondary importance, may rapidly rise to the position of 

 serious pests. H. cervinus and P. signifer in particular are likely to> 

 be troublesome. 



King (H. H.). Clean Cultivation and its Relation to the Control of 

 Insect Pests. — Wellcome Trop. Res. Lab., Khartoum, Entom, Bull.. 

 8, 17th March 1918, 4 pp. [Received 28th February 1920.] 



It is suggested that the importance of the suppression of weeds, 

 and clean cultivation generally in the control of insect pests is usually 

 underestimated or not reahsed at all. In tliis connection it should 

 be remembered that, while some insects in the Sudan have only one 

 food-plant, such as Diparopsis castanea (red cotton bollworm) and 

 Aphis sorghi (dura aphis) and others, such as locusts, grasshoppers, 

 crickets and cutworms, are practically omnivorous, the majority of 

 species have two or several food-plants. Earias insulana (spiny cotton 

 bollworm) and Nisotra uniformis (cotton flea-beetle), for example,. 

 can feed on Hibiscus esc.ulentus, H. sabdariffa and Abutilon spp., all 

 of which are allied to cotton. Tlie dura stem-borer \Sesamia creticaj 

 attacks both maize and wheat, and a bug, Agonoscelis puberula, 

 which sometimes greatly damages dura, feeds also on wild grasses. The 

 cotton aphis [Aphis gossypii] has for alternative food-plants members 

 of the melon family (Cucurbitaceae) which are in no way related ta 

 cotton. Cotton should not occupy the land for more than ten months 

 in the year ; dura, the staple crop of sakia land, is not generally 

 grown in the winter, wliile barley, wheat, beaus. Hibiscus, etc., rarely 

 take more than four months from seed time to harvest. 



General recommendations are that the entire farm and uncultivated 

 land immediately adjoining it should be kept as far as possible free 

 from weeds. Canal banks, waste land near buildings and land under 

 bare fallow, should receive particular attention. Plants growing in 

 these situations are almost always useless and inedible for stock. 

 On farms plants should be rigidly restricted to the areas on wliich they 

 have been sown. All diseased plants and fruits should be destroyed. 

 Melons infested with Dacus brevistylus (melon fruit-fly) should not be 

 left on the ground, where the maggots can complete development, 

 but should be thrown into water. The refuse of a crop that has been 

 harvested should be at once collected and burned. In this way, in the 

 case of melon plants, numbers of Aspongopus viduatus (black melon 

 bug) will be Idlled. Refuse of cotton and dura should never be used 

 for building shelters or windscreens, as it frequently harbours numbers 

 of stem-borers or other pests. Ploughing should take place as soon as 

 possible after harvest. 



King (H. H.). The Control of Insect Pests of Cotton. — Wellcome 

 Trop. Res. Lab., Khartoum, Entom. Bull. 9, 13th August 1918, 

 4 pp. [Received 28th February 1920.] 



The principal pests of cotton in the Anglo-Egyptian Sudan include : 

 Pectinojjhora gossypiella (pink bollworm), Earias insulana (spiny 

 bollworm), Diparopsis castanea (Sudan or red bollworm), Aphis 

 gossypii (cotton aphis or asal fly), Oxycarenus hyalinipennis (cotton 



