EKPOET ON ECONOMIC ENTOMOLOGY 
227 
During the last week of March, 1907, asal tly was reported from the district between 
Sliendi and Gebel Uinali. By the time I arrived there most of tlie infested dura had 
been reaped, but at one place some was still standing. The plants were alive hut literally 
smothered with honeydew, and even the ground underneath them was caked with it. The 
fly itself, however, had left the dura, and a careful search failed to reveal any aphis either 
above or below ground on any plants growing in the vicinity. 
Xatiiral enemies .—Chief among the natural enemies of the asal fly are several species 
of lady-bird beetles, which, in hotli their larval and adult stages, feed freely on the aphides 
and the larva of an undetermined species of Syrphus fly. These and other predaceous 
insects do a certain amount of good, and sometimes completely stamp out an attack while 
still in its early stages. On several occasions this has been the case on the dura grown 
in the Gordon College garden, where there are always considerable numbers of lady-hird 
beetles and Syrphus flies to be found. Usually, however, these beneficial insects are not 
sufflciently plentiful when the asal fly makes its appearance to do any a])preciable good, 
and by the time their numbers have increased the damage has been done. 
The injury suffered by the crop is probably due more to the smothering of the leaves 
with honeydew than to the actual loss of sap sucked out by the insects. 
Much remains to be learned of the life-history of this pest. As above stated, it 
probably, on leaving the dura, migrates to some other plant, where, possibly in an altered 
form, it spends that part of the year when it is not to be found on the dura. 
Another species of aphis attacks dura but has not as yet been seen occurring in sufficient 
numbers to be worthy of the rank of a pest. It is usually found in the growing point of 
the plant or between the sheathing leaf and the head of corn. 
M I L LI r E n E A T T .\ C K I N G D U K H N 
Jttlus, sp. 
A large millipede, locally known as Surrfa, is a pest of some importance in parts of 
Kordofan, where it is said to attack the roots of dukhn. 
It is about 11 cm. in length and in colour dark brown, with the bases of the somites 
paler. 
The millipedes are not true insects, but belong to the group known as ^[yriapoda. The 
Myriapoda are divided into five orders—the two more important ones being the Ghilognaiha 
or millipedes and the Ghilopoda or centipedes. The latter are usually beneficial to man, 
being carnivorous in their habits, and so helping to keep in check some of the noxious 
insects. They possess onlj^ one pair of legs to each body ring and can thus be distinguished 
from the millipedes, which are provided with two pairs to each segment. 
Some of the larger centipedes are capable of inflicting a very poisonous bite when 
incautiously handled. 
The millipedes, known in England as false irire warms, are mainly vegetarians, feeding 
both on decaying organic matter and living plants. They have also been recorded to 
devour slugs, snails, etc. They are incapable of biting when handled, but some of them 
can emit a very evil smelling liquid. 
Several species of millipedes occur in England as farm pests, attacking mangolds, 
beets, potatoes, strawberries, etc. 
The following is a brief outline of the life-history of ,lulus terrestris, one of the more 
common of the millipedes found in England. 
Natural 
enemies of 
the aphis 
Millipedes 
