297 
COLOUR CONVENTIONS TO INDICATE THE DISTRIBUTION 
OF BLOOD-SUCKING INSECTS AND THE DISEASES 
THEY TRANSMIT. 
By Jas. J. Stmpson, M.A., D.Sc. 
(PratEe VI.) 
The necessity for graphic representation of the distribution of insects and the 
diseases which are transmitted by them is now so evident as to need no special 
demonstration. But it is further obviously important that some uniform method 
should be adopted in the preparation of such maps, in order to make them inter- 
comparable, and the object of the present notes is to suggest a comprehensive 
system of notation for the whole genus Gloss’na—a system which may be readily 
adapted for use in other genera or families of blood-sucking insects. 
The only scheme hitherto adopted was that used in the maps published by the 
Sleeping Sickness Bureau in which red was restricted to sleeping sickness, brown 
to Glossina tachinoides, blue to Glossina palpalis, green to Glossina morsitans and 
G. pallidipes, and yellow to Glossina fusca. At the time when that scheme was 
formulated the recognised species of Glossina were much fewer than at present 
and their bionomics were less perfectly known. Further, the records of Glossina 
morsitans and G, pallidipes were not sufficiently exact to permit of discrimination 
between the two species and one colour had consequently to be used to include 
both. 
Recent work has shown more emphatically than ever that such distinctions are 
not only advisable, but necessary, and this, combined with the fact that several 
new species have recently been described, renders it impossible to assign to each 
of the species a definite colour sufficiently distinctive to avoid confusion. This 
will be at once evident when it is remembered that there are, at present, seventeen 
species of Glossina more or less universally recognised. Some of them are, 
however, subjects of controversy, but until such disputes are definitely settled we 
must take note of them separately. Moreover, in the event of any so-called 
species being either submerged or proved to be distinct, it will be much easier, 
and lead to less confusion, to group two series of conventions, already published, 
into one, than to divide one series into two or more. In fact, the latter procedure 
is possible only after a re-examination of all the specimens so recorded—an 
almost impossible task. 
So far, only sleeping sickness and Glossina have been considered, but it may 
be found advisable also to record graphically other diseases and their carriers, 
for example, yellow fever and Stegomyia fasciata. For the present it is proposed to 
deal only with the former, but it will be evident that should maps be required 
for the latter a similar system of notation could be employed. 
If we recognise, therefore, the necessity for representing graphically the 
distribution of sleeping sickness and of seventeen species of Glossina and ihe 
22036 B 2 
