289 
This  was  seen  more  particularly  along  the  coast  oi  Lake  Tanganyika  in  several 
of  the  small  bays  which  were  closed  in  by  precipitous  cliffs.  'tVe  landed  at  these 
from  a  canoe,  and  caught  both  species  together. 
They  are  more  resistant  to  changes  of  temperature  than  GL. 
palfialis,  and  will  flourish  at  much  greater  altitudes  ;  in  many  places 
we  have  caught  them  well  over  four  thousand  feet  above  sea  level. 
They  are  said  to  shun  human  habitations ;  this  depends,  apparently, 
to  some  extent  on  the  character  of  the  village,  that  is  to  say,  whether 
it  is  clean  and  well-kept  or  whether  the  spaces  between  the  huts  are 
utilised  to  grow  such  crops  as  cassava,  for  in  such  we  have  caught 
Gl.  morsitans. 
Tor  instance,  they  have  come  into  the  tent  when  pitched  in  a  village,  and  have 
been  caught  in  another  while  we  were  palpating  the  people. 
This  condition,  however,  is  rather  unusual  in  most  parts  of  the 
country,  so  that  it  is  rather  rare  to  see  the  fly  actually  inside  the 
villages. 
It  may  be  as  well,  in  view  of  Koch’s*  statement  that  Gl. 
morsilans  in  German  East  Africa  will  not  attack  men,  to  say  that 
the  Rhodesia  and  Nyasaland  varieties  do  not  hesitate  to  do  so, 
and  wherever  they  are  met  they  become  a  veritable  pest. 
The  pain  felt  when  a  tsetse  fly  bites  is  variable.  It  may  be  so 
acute  as  to  feel  like  a  red-hot  needle,  or,  on  the  other  hand,  it  may  be 
quite  painless.  This  depends  altogether  on  the  spot  they  select.  As 
a  rule,  no  after-effects  are  noticeable  at  the  site  of  the  bite.  In  those 
cases  where  the  fly  experienced  any  difficulty  in  getting  through  cloth, 
it  would  very  frequently  cause  the  wings  to  vibrate  very  quickly,  with 
a  sharp  buzzing  sound,  as  if  it  were  trying  to  bore  through  the 
obstruction.  This  buzzing  sound  is  most  distinctive,  and  often  is  the 
first  thing  which  draws  the  attention  to  the  presence  of  the  flies  when 
they  are  very  scanty  and  difficult  to  catch. 
After  making  all  allowance  for  lack  of  sufficient  observation,  there 
can  be  little  dotibt  that  Gl.  morsitans  is  increasing  in  numbers  in 
these  countries.  This  statement  is  made  by  all  the  Europeans  who 
have  been  in  the  territory  for  any  number  of  years,  and  while  many  of 
them  have  only  taken  an  interest  in  the  question  since  Sleeping 
Sickness  htis  become  so  prominent  a  subject,  and  may,  therefore,  be 
jumping  to  the  conclusion,  definite  evidence  exists  in  some  cases. 
*Koch .  loc.  cit. 
T 
