Acarine  Pests. 
283 
ACARINE  PESTS. 
Some  of  the  most  formidable  enemies  of  the  agriculturist 
do  not  belong  to  the  group  of  insects,  but  to  the  acari  or  mites, 
and  several  of  these  creatures  were  the  subject  of  inquiry  during 
the  past  season.  In  previous  Reports,  instances  of  alleged  injury 
by  members  of  the  usually  harmless  group  of  beetle  mites 
(Oribatid®)  have  been  recorded,  and  these  have  again  attracted 
attention.  Further  investigation  shows  that  the  most  common 
offender  is  not  Orihata  orhicularis.,  but  the  very  similar  O.  lapi- 
daria,  although  in  one  case  the  mite  complained  of  turned  out 
to  be  Notaspis  hicorum.  If  these  creatures  are  really  injurious 
they  do  harm  by  congregating  in  large  numbers  on  the  bark  of 
trees,  especially  lime  trees,  and  setting  up  a sort  of  cankerous 
growth  which  spreads  until  it  covers  quite  a considerable  area. 
They  seem  to  choose,  by  preference,  the  point  just  below  the 
base  of  a branch,  where  they  look  like  a cluster  of  shining 
brown  eggs  ; and  if  a tree  is  observed  to  be  infested  in  this 
manner  it  would  be  a wise  precaution  to  remove  the  mites  in 
some  way.  The  alkali  wash,  recommended  for  winter  use  in 
my  article  on  “ Orchard  and  Bush  Fruit  Pests,”  * would  be 
effectual  against  this  as  against  other  creatures  harbouring  in 
the  bark. 
Some  mites  occurring  in  large  numbers  in  daffodil  bulbs 
were  sent  for  identification,  and  proved  to  be  Rhizoglyphus 
echinopus.,  a creature  of  the  cheese  mite  type.  It  was  probably, 
however,  of  little  importance,  and  merely  an  indication  of  the 
rotten  condition  of  the  bulbs. 
The  highly  destructive  mites  known  as  “red  spider”  were 
complained  of  in  several  districts ; but  they  are,  unfortunately, 
too  familiar  to  require  more  than  a brief  notice.  The  difficulty 
of  eradicating  them  is  chiefly  due  to  two  facts — they  are  pro- 
tected under  the  leaves  of  the  plant  they  infest  by  the  closely 
interwoven  threads  which  they  spin,  and  their  eggs  have  such 
tough  shells  that  they  resist  any  insecticide  which  it  is  safe  to 
use.  It  is,  therefore,  necessary  to  wash  with  some  fluid — like 
paraffin  emulsion  with  soft  soap  added — which  will  cling  well 
to  the  leaves,  and  to  repeat  the  washing  at  short  intervals  to 
kill  successive  broods. 
Another  acarine  pest  now  almost  universally  known  is  the 
Black-currant  Gall-  Mite,  which  causes  “ big  bud.”  Several 
members  of  the  Society  have  availed  themselves  of  the 
information  obtained  by  the  Zoologist  as  to  localities  from 
which  mite-free  black-currant  plants  can  be  procured  ; and  the 
number  of  samples  of  suspected  shoots  sent  for  examination 
testifies  to  the  interest  which  has  been  awakened  in  this 
^ Journal  R.A.S.E.,  Vol.  63,  1902,  page  118. 
