.iunc  L6,  1902. 
JOURNAL  OF  IIOllTICULTUUE  AND  COTI'AIK  GABDENER, 
551 
The  Cclorado  Beetle. 
This  Potato  pe.st,  Doryphora  (Leptinotarsa)  deceialineata 
(S^ay))  is  a  beetle  now  also  known  as  Lejjtinotarsa.  This  <fenus 
.seems  to  be  tropical,  Central  America  being  its  apparent  home, 
although  some  species,  including  the  Colorado  Beetle  or  Spear¬ 
man  occur  in  North  America. 
The  adult  female  beetle  is  a  little  under  half  an  inch  in 
length,  the  male  being  slightly  smaller  than  the  feinale.  In 
colour  the  beetle  is  yellow,  with  five  longitudinal  dark  lines  on 
each  wing  case  ;  the  legs  are  reddish  with  dark  knee  spots  and 
feet;  the  yellow  mesothorax  has  also  a  few  dark  spots  and  a  more 
or  less  irregular  Y-shaped  mark  in  the  middle  :  the  wings  have 
a  peculiar  rosy  line,  which  is  ]5articularly  noticeable  vdien  the 
b^tle  is  flying  in  the  sun.  The  adult  hibernates  during  the 
winter  months  under  any  rubbish  it  can  find,  but  especially 
buried  beneath  the  surface  of  the  ground.  Its  general  depth  in 
the  soil  during  the  winter  seems  to  vary  from  a  few  cO'  24  inches. 
Riley  says  it  has  been  exhumed  from  a  few  inehe,s  to  several  feet, 
though  its  habit  is  not  to  burrow'  deeper  than  lOin. 
The  beetles  come  from  their  winter  quarters  when  the 
weather  become.^  warm  in  spring.  They  are  capable  of  flying 
some  considerable  distance,  e.specially  taking  wing  readily  in 
the  early  part  of  the  year.  The  warmer  the  day  the  more 
willingly  do  the  insects  fly. 
The  eggs  are  elongated  oval  in 
form,  of  an  orange  colour,  and 
are  deposited  in  clusters  of 
from  nine  to  forty.  They  seem 
to  be  nearly  always  placed  on 
the  under  side  of  the  leaf,  and 
are  attached  to  it  by  one  end. 
They  resemble  the  ova  of  some 
of  the  Coccinellidse  or  lady¬ 
birds,  but  are  much  larger  than 
those  of  any  of  our  native 
.species.  Riley  says  they  hatch 
out  in  less  than  a  w'eek ;  those 
under  observation  were  kept 
ten  days  before  the  larvse 
came  out.  The  females  com¬ 
mence  to  deposit  their  eggs 
when  the  plants  are  quite 
young.  The  young  larvae  are 
of  a  dull  reddish-brown  colour, 
and  bear  some  resemblance  to 
the  larvae  of  ladybirds.  As 
they  grow  they  become  paler  in 
colour,  varying  from  dull  brick- 
dust  red  to  almo.st  orange  in 
hue,  w’ith  the  head,  legs  and 
posterior  part  of  the  first  seg¬ 
ment  black,  and  with  two 
lateral  rows  of  black  tubercle¬ 
like  spots,  the  upper  row'  being 
the  largest  and  composed  of 
seven  spots.  As  the  larvae  be¬ 
come  mature,  the  body  is  some- 
wdiat  swollen  and  more  or  less 
arched,  the  apex  terminating 
in  a  kind  of  sucker,  the  upper 
part  of  the  tw'o  apical  seg¬ 
ments  being  black.  When 
full  grown  the  larvae  is  rather  more  than  half  an  inch  long 
when  extended. 
The  leafage  is  devoured  very  ravenously  at  times  by  the 
larvae,  W'hich  attach  themselves  to  both  upper  and  under  sides 
and  the  edges  of  the  leaves.  They  are  also  said  to  feed  on  the 
stalk,  so  that  the  whole  Potato  haulm  is  attacked.  When 
mature,  the  larvae  fall  to  the  ground  and  burrow'^  under  the  soil 
and  there  pupate.  In  America  this  stage  seems  to  last  a  w^eck, 
for  Riley,  after  stating  that  the  larv^  mature  in  from  twm  to 
three  weeks,  .says  “  the  beetle  .stage  is  assumed  in  about  a  month 
from  the  time  of  hatching.”  How'  many  broods  might  appear 
in  Great  Britain  is  not  known.  As  many  as  three  are  observed 
in  North  America,  and  there  is  no  reason  why  three  broods 
should  not  also  occur  in  this  countiy,  as  the  larvae  seem  to  grow 
very  rapidly. 
When  tiie  weather  commences  to  become  cold  in  the  autumn 
the  beetles  bury  them.selves  in  the  earth,  where  they  shelter 
during  the  winter,  as  well  as  amongst  rough  herbage  and  under 
rubbish  of  all  kinds.  The  beetles  are  extremely  hardy,  and  can 
withstand  a  large  amount  of  rough  usage.  Both  larva  and  adidt 
can  eject  a  dark  fluid,  which  is  thought  by  some  to  be  poisonous, 
but  W'hich  seems  quite  innocuous. 
Its  Food  Plants. 
There  is  no  doubt  that  when  pressed  for  food  this  beetle  will 
take  to  a  great  number  of  plants  besides  the  Potato.  In  its 
Phaltenopsis  Schilleriana. 
native  home  it  mainly  feeds,  under  natural  conditions,  on  two 
wild  species  of  Solanum,  S.  rostratum  and  S.  cornutum.  Ihe 
Solanacese,  or  Nightshade  and  Potato  family,  form  its  .staple 
diet,  especially  the  genus  Solanum.  The  other  species  upon 
which  the  larvse  have  been  found  in  America-  are  the  following: 
The  common  Horse  Nettle  (S.  Carolinense),  found  in  Missouri 
and  east  of  +he  Mississippi ;  S.  I’obustum,  S.  discolor,  S. 
Sieglingi,  and  S.  M’arscewiczi. 
The  closely  related  Tomato  (Lycopersicum),  the  Ihorn  Apple 
(Datura),  the  Henbane  (Hyoscyanius),  the  Tobacco  plant 
(Nicotiana),  the  Apple  of  Peru  (Nicandra),  the  Ground  Cherry 
(Physalis),  Belladonna,  and  Petunia  have  also  been  recorded  as 
nourishing  this  pest,  but  upon  scarcely  any  can  it  flourish  except 
the  Tomato. 
Various  Poppies,  especially  the  Mexican  or  prickly  Poppy 
(Argemone  Mexicana),  also  serve  as  food  plants  in  America. 
From  the  States  it  has  also  been  recorded  feeding  on  the  follow¬ 
ing:  The  Pigweed  (Amaranthus  retroflexus),  the  Hedge  Mustard 
(Sisymbrium  cflicitiale).  Oats,  Smart-weed  (Polygonum  hydro- 
piper),  the  Red  Currant,  various  Thistles,  Gcosefoot  (Cheno- 
podium  hybridum),  Thorough-wort  (Eupatoriuni  perfoliatum), 
the  European  Black  Henbane  (Hyoscyamus  niger),  and  the 
Mullein  (Verba, scum). 
Grasses  and  other  weeds  have  been  known  to  harbour  th  ■ 
larv8e.  In  some  allotments  at  Tilbury  Docks,  where  in  1901 
an  isolated  colony  of  these  beetles  was  found  and  destroyed, 
the  larvse  were  observed  feeding 
on  IVoody  Nightshade,  Cabbage, 
and  Thistle.s,  whilst  the  egvs 
were  found  in  one  case  on  th;? 
Sowthistle  (Sonchus).  It  thus 
seems  that  although  members 
of  the  genus  Solanum  are  its 
chief  diet,  especially  the  cul¬ 
tivated  Potato  (where  its 
’original  food  plants  do  not 
occur),  both  larvae  and  adulhs 
can  feed  on  a  variety  of  other 
plants,  preferably  devouring  the 
young  leave.s. 
Its  Natural  Enemies. 
A  great  number  of  natural 
enemies  tend  to  check  the 
beetle  in  America.  Among.st 
these  are  birds  which  feed 
upon  both  larvae  and  adults, 
especially  the  rose-breasted 
grosbeak  (Guiraca  ludoviciana). 
Both  ducks  and  chickens,  but 
especially  the  former,  devour 
the  larvae.  The  toad  in  America 
(Bufo  Americana)  gorges  itself 
Avith  the  grubs,  and  probably 
our  British  species  Avould  do 
the  same. 
Very  numerous  are  the  insect 
enemies  i-ecorded  by  Riley, 
especially  amongst  the  beetles 
or  Coleoptera,  and  the  bugs,  or 
Hemiptera-heteroptera.  Strange 
to  say,  no  members  of  the 
Hynienoptera,  the  order  that 
contains  so  many  parasites,  are 
actually  parasitic  on  Doryphora;  a  single  species  o.f 
(Polistes  rubiginosus),  however,  occasionally  provisions  its  nes 
with  the  larvae. 
Whilst  examining  the  allotments  at  Tilbury,  the  large  seven- 
spotted  ladybird  (Coccinella  septeni-punctata)  wa.s  noticed  m 
considerable  numbers  both  in  adult  and  larval  stages, 
larvae  were  seen  in  one  instance  devouring  the  eggs  o 
Colorjido  beetle,  and  when  placed  in  a  box  with  ate  them 
ravenously.  Thus  in  the  short  space  of  time  in  vv  i 
Potato  pest  existed  in  this  country  it  found 
which,  on  account  of  its  ravenous  nature,  could  not  but  help 
materially  in  cliecking  its  increase. 
The  pupa  of  the  ladybird  is  orange  vvith  black 
spots,  and  resembles  very  closely  the  small  grub  of  the 
beetle.  A  small  Hemipteron,  a  green  Nemocoris  (?)  atso 
seen  wandering  about  amongst  the  larv^,_  and  may 
feeding  off  them,  sucking  out  the  body  juices  in  the  same  way 
as  several  species  do  in  America.  . 
If  this  beetle  is  found  it  is  important  to  1’®“^®^^!®®'^ , 
under  the  terms  of  the  “Colorado  Beetle 
notice  must  be  given  at  once  to  a  consitable.  Ihe 
is  then  required  to  communicate  immediately  with  the  loc^ 
authority,  who  shall  forthwith  give  notice  by  telegraph  to 
the  Board  of  Agriculture. — 4,  Whitehall  Place,  London,  S.W., 
March,  1902. 
