ENNOMOS  SUBSIGNARIA,  OR  THE  MEASURING  WORM.  305 
ENNOMOS   SUBSIGNARIA,  OR  THE  MEASURING-WORM. 
By  Allen  Shryock. 
(An  Inaugural  Essay,  presented  to  the  Philadelphia  College  of  Pharmacy.) 
Class  Insecta.  Order  Lepidoptera  (Linn.)  Tribe  Gceometra 
(Hiibner). 
General  Characteristics. — Head  roundish,  furrowed  above,  and 
of  a  pale  red  color.  The  male  and  female  are  furnished  with  ten 
legs ;  six  in  front,  which  are  horny  and  jointed,  tapered,  and 
placed  beneath  the  first  three  rings  of  the  body.  The  remaining 
four  are  placed  beneath  the  extremities,  and  are  thick,  fleshy 
and  jointed.  The  body  is  fiom  six  to  twenty  lines  in  length, 
and  slate-colored.  The  imago  is  pure  white  on  the  upper  side, 
with  slight  brown  tips  on  the  upper  surface.  The  females  are 
longer  in  body  and  wings,  and  are  rather  lazy.  Both  male  and 
female  have  full  use  of  their  wings.  The  male  antennae  is  pecti- 
nated underneath  to  the  tip  ;  the  female  antennae  is  filiform, 
notched  beneath. 
About  the  end  of  the  first  week  in  July  the  female  deposits 
her  eggs,  usually  numbering  about  fifty  or  more,  upon  the  lower 
bark  of  the  trees  upon  which  they  feed.  They  are  most  generally 
seen  upon  the  different  species  of  maple,  but  at  times  they  are 
seen  upon  our  fruit  trees.  After  depositing  these  eggs  they  die, 
and  by  the  middle  of  the  next  June  the  eggs  are  matured  into 
the  larvae,  which  suspend  themselves  from  the  upper  branches  of 
the  trees  by  a  silk  cord  in  the  warm  sun,  which  is  their  delight; 
at  night  they  draw  in  the  cord.  They  cause  great  havoc  among 
the  leaves.  When  in  danger  they  remain  for  several  hours  in 
the  same  position,  resembling  the  twig  to  which  they  are 
attached. 
The  tribe  derives  its  name  Geometra  from  the  fact  that  its 
members  measure  (as  it  were)  the  ground  over  which  they  pass.. 
They  cast  their  skin  several  times  during  the  season.  The  male 
larvae  of  this  particular  type  are  the  smallest,  and  most  active. 
They  are  most  abundant  in  large  cities,  in  which  they  are  justly 
regarded  as  a  great  pest ;  in  the  country  they  are  much  less 
common,  as  they  are  soon  devoured  by  the  birds.  I'have  seen, 
some  few  upon  the  oak  in  the  south-central  part  of  our  State. 
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