42 



INSECTS AND VEGETABLE PARASITES INJURIOUS TO CROPS 



Scale insects 



Difiiculty of 

 combating liie 

 aphides in 

 the Sudan 



\alue of 

 lady Bird 

 beetles 



of the leaves, hindoriiig the ])lant respirations by their secretion, and destroying 

 the young ears of grain -whik' they are yet soft. It is easy to recognise an infected 

 plant fi-om the shiny stickiness on the leaves, the deposit on the groimd, sometimes 

 veiy copious, and the vast number of pale larva; and so-called plant-lice. The 

 acacia arabica, (sant tree), is liable to be attacked by a scale insect which forms 

 little white balls (ni the twigs. Specimens of this and of all the Aphides have 

 been sent to Mr. Theobald. The acacia insects were given me by Mi-s. Broun, 

 the Honorary Secretary of the Museum Board. Slie had collected them on the 

 White Nile." 



The Aphis has formed the subject of sevei'al reports to the Secretary General, 

 but it is evident that in a comitry like the Sudan it is very difficult to employ 

 suitable preventive methods. No doubt petroleum, naphthalene and (piassia waslies 

 and sprays are effective, but they have to be properly and judiciously applied, 

 and in many cases spraying apparatus would be required. Burning of infected 

 grain would be beneficial, the planting of the castor-oil plant round the fields is said 

 to be useful, and something might be accomplished by merely squirting Avater 

 through a hose on the plants and thus washing off the insects, but the outlook 

 is scarcely hopeful in this direction. The question of the utility of lady-bird 

 beetles, (Coccinellidi«), which along with their Larvae feed greedily on the Aphides, 

 is an important one. Mr. Brovin noticed a lady-bird l)usy on infected plants in the 

 Bahr-El-Ghazal. I found fragments of lady-birds in the dui-a specimens fi-om 

 Kassala and Sennar, and discovered the following species present in large numbers 

 on the "Asal" dui-a in Khartoum. Mr. Theobald kindly identified them 

 f ( )r me as — 



Cliilomenes vicina, Muls. 



CoccineUa. ll-jniDctata. 



Specimens of these were secured and mounted and entomologists in South 

 Africa were commnniciited with, as American lady-birds have been introduced 

 there to combat Scale Insects and Aphides. 



The information obtained has been sent to the Secretary General, and it is 

 probal)le that in the Coccinellidie, either those which are indigenous or species which 

 may be imported, we have the best means of attacking the fly. At the same time 

 it must be confe.ssed that the reports received are none too encouraging. The 

 Aphides are themselves hable at times to invasion by a fungus {Entoiaojihtora 

 aphidis), which destroys them wholesale. It seems worth while considering if tliis 

 could not be utilised, but the whole question is really one for a skilled entomologist. 

 It Avill no (lou])t receive due attention from the official recently appointed for the 

 purpose by Lord Cromer. Meanwhile information has been fm-nished with regard 

 to approjiriate washes and how they are best employed, and here again I would 

 express my indebtedness to ^Ir. Theobald, to the Agricultural Bureau at \\'ashington, 

 U.S.A., and to the South Eastern Agricultural College at Wye, Kent, England. 



