﻿New 
  York 
  State 
  Museum 
  

  

  SCALE 
  INSECTS 
  (DIASPINAE) 
  OF 
  IMPORTANCE 
  

  

  Ord. 
  Hemiptera: 
  Fam. 
  Coccidae 
  

   INTRODUCTION 
  

  

  "There 
  is 
  no 
  group 
  of 
  insects 
  which 
  is 
  of 
  greater 
  interest 
  to 
  horticul- 
  

   turists 
  today 
  than 
  that 
  family 
  which 
  includes 
  the 
  creatures 
  popularly 
  

   known 
  as 
  ' 
  scale 
  insects 
  ' 
  and 
  ' 
  mealy 
  bugs,' 
  " 
  These 
  words, 
  written 
  20 
  

   years 
  ago 
  by 
  Prof. 
  Comstock, 
  the 
  first 
  American 
  to 
  make 
  a 
  close 
  study 
  of 
  

   the 
  characters 
  presented 
  by 
  the 
  female 
  scale 
  insect, 
  are 
  still 
  true. 
  These 
  

   insignificant 
  animals 
  attack 
  almost 
  every 
  tree 
  and 
  shrub 
  and 
  many 
  

   herbaceous 
  plants, 
  and 
  certain 
  species 
  have 
  caused 
  serious 
  injuries 
  and, 
  

   under 
  favoring 
  conditions, 
  are 
  capable 
  of 
  inflicting 
  enormous 
  losses 
  on 
  

   our 
  nursery, 
  orchard 
  and 
  greenhouse 
  interests. 
  Their 
  minute 
  size, 
  resis- 
  

   tance 
  to 
  insecticides 
  and 
  marvelous 
  prolificacy 
  render 
  them 
  formidable 
  

   pests. 
  Scientific 
  men 
  have 
  awakened 
  to 
  the 
  importance 
  of 
  this 
  group, 
  

   and 
  scale 
  insects 
  are 
  being 
  studied 
  as 
  never 
  before. 
  Large 
  numbers 
  of 
  

   new 
  species 
  have 
  been 
  characterized 
  within 
  the 
  last 
  five 
  years, 
  and 
  -many 
  

   important 
  biologic 
  facts 
  relating 
  to 
  this 
  family 
  have 
  been 
  ascertained. 
  

  

  Characteristics. 
  The 
  popular 
  name, 
  " 
  scale 
  insects," 
  is 
  truly 
  de- 
  

   scriptive 
  of 
  the 
  species 
  belonging 
  to 
  one 
  subfamily, 
  the 
  Diaspinae, 
  or 
  

   armored 
  scales, 
  since 
  the 
  insects 
  themselves 
  are 
  covered 
  with 
  a 
  scale, 
  a 
  

   secretion 
  usually 
  beginning 
  on 
  the 
  recently 
  hatched 
  young 
  as 
  a 
  mass 
  of 
  

   white, 
  cotton-like 
  threads 
  (pi. 
  i, 
  fig. 
  3), 
  which 
  mats 
  down 
  and 
  extends 
  to 
  

   form 
  a 
  shield-like 
  covering 
  for 
  the 
  tender 
  insect 
  (pi. 
  i, 
  fig. 
  4). 
  These 
  

   forms 
  are 
  frequently 
  known 
  as 
  bark 
  lice,, 
  because 
  most 
  of 
  the 
  species 
  are 
  

   found 
  on 
  the 
  bark 
  of 
  trees 
  or 
  shrubs, 
  and 
  it 
  is 
  a 
  very 
  good 
  descriptive 
  

   name. 
  The 
  scale 
  insects, 
  like 
  all 
  others 
  belonging 
  to 
  the 
  same 
  class, 
  

   originate 
  from 
  eggs. 
  Sometimes 
  the 
  eggs 
  are 
  deposited 
  under 
  the 
  scale 
  

   (pi. 
  I, 
  fig. 
  8) 
  and 
  remain 
  unhatched 
  over 
  winter, 
  or 
  they 
  may 
  develop 
  into 
  

   young 
  within 
  the 
  body 
  of 
  the 
  female 
  (pi. 
  3, 
  fig. 
  10), 
  and 
  then 
  the 
  insect 
  is 
  

   called 
  viviparous, 
  or 
  more 
  strictly, 
  ovoviviparous. 
  The 
  young 
  in 
  either 
  

   case 
  are 
  minute 
  creatures 
  possessing 
  six 
  true 
  legs, 
  with 
  good 
  locomotive 
  

   powers 
  for 
  such 
  small 
  beings, 
  and 
  provided 
  with 
  eyes 
  and 
  a 
  pair 
  of 
  

   antennae 
  or 
  feelers. 
  That 
  is, 
  they 
  have 
  the 
  normal 
  characteristics 
  of 
  

   very 
  young 
  insects. 
  The 
  secretion 
  of 
  the 
  scale, 
  which 
  usually 
  begins 
  

   within 
  a 
  few 
  days 
  after 
  the 
  young 
  hatch, 
  is 
  followed 
  by 
  remarkable 
  

   changes. 
  The 
  eyes, 
  antennae 
  and 
  legs 
  disappear, 
  and 
  there 
  results 
  an 
  

   animated, 
  sucking, 
  sac-hke 
  creature 
  (pi. 
  i, 
  fig. 
  10) 
  with 
  apparently 
  no 
  

  

  