3U 



that none happened to be observed. Usually not more than about 1 per 

 cent, of the adult leaf -hoppers are found to be parasitised, and when 

 cocoons of the parasite are collected in the field, hyp^erparasites issue 

 from a large proportion of them, thus reducing the efficiency of the 

 parasite. This Dryinid attacks the adult J,eaf-hoppers, immature 

 individuals being only rarely parasitised by it ; in this respect it 

 differs from Echthrodelphax fairchildi and Haplogonatopus vitiensis, 

 both of which attack the young leaf -hoppers and only rarely an adult. 

 The egg is inserted in the dorsal part of the abdomen. The leaf- 

 hopper dies when the parasite becomes full-grow^n, and the latter 

 spins a cocoon on a leaf or on the sugar-cane stalk itself, about 3 or 4 

 Aveeks being spent in this stage ; the whole hfe-cycle occupies 4 to 6 

 weeks. In the laboratory a female Dryinid lived 37 days and parasitised 

 153 leaf -hoppers, showiag how great would be its value if it were not 

 hyperparasitised. 



Jack (R. W.). Maize Culture on Red Soil : Value of Poisoned Bait as 

 an Aid to good Stands. — Rhodesia Agric. Jl., SqlishHry, x.yi, no. 2, 

 April 1919, pp. 107-112, 1 fig. Also issued as Rhodesia Dept. 

 Agric, Salisbury, Bull. no. 317, April 1919, 8 pp., 1 fig. 



It is estimated that the average stand of vigorous maize plants on 

 red soil in Rhodesia is 60 to 70 per cent. , the greater part of the des- 

 truction of the remainder being due to insect pests. The soil within 

 a few inches of the surface supports a good deal of insect life in an 

 immature condition during the dry season, and the adults, many of 

 which are plant -feeders, emerge just about the conunencement of the 

 rains. As soon as the plants begin to appear they are attacked eagerly 

 by these insects, the seed, the shoot before it reaches the surface, 

 or the young plant, all being Hable to attack. The insects that affect 

 the stand of maize, apart from those that attack the plant after it 

 has become established, such as maize stalk borer [Busseola fusca], 

 include two species of surface beetles, Gonocephalum aequale and 

 Emyon tristis. The eggs of these beetles are laid loosely in the soil 

 from late March throughout the dry season and in greatly reduced 

 numbers after July. The larvae feed upon dry vegetable matter in 

 the soil, but will eat into dry seeds if these are available. The majority 

 have completed their gro\\i:h by November and pupate in the soil, the 

 adults emerging in two or three weeks. The adults five until late 

 March before beginning oviposition, and in this stage only are des- 

 tructive to the maize crop. Two species of weevils occur, namely 

 Systates sp. and Tanymecus sp. The life-histories of these are not 

 accurately known, but the larvae seem to five in the soil and feed upon 

 the roots of certain weeds or native plants. The adults are active 

 in. late November and are often present about the soil before the crop 

 is planted. Field crickets, grasshoppers, cutworms and wire worms 

 {Trachynotus sp.) are also injurious to the stand of maize. None of 

 these insects are specific maize pests, but with the exception of grass- 

 hoppers and possibly crickets, they seem to flourish better under 

 conditions of cultivation than under natural ones. This is due to 

 the greater looseness or penetrabihty of cultivated soils and the fact 

 that cultivation encourages the growth of weeds other than grasses. 



