Basic  Entomology  for  Iden4fiers    

Carlos E. Bográn, PhD Associate Professor & Extension Specialist c-bogran@tamu.edu

TDA  Inspector  Training,  2012  

• Basic  Entomology  – What  is  an  insect?    – Biology  and  development  – Common  insect  groups  – Iden4fica4on,  diagnosis  

Outline

What  type  of  animal  is  an  insect?  •  Insects  are  arthropods  in  the  Class  Hexapoda  (six-­‐legged)    

•  Invertebrates  (lack  back-­‐bone)  with  exoskeletons  and  segmented  bodies  

• Ventral  nerve  cord;  dorsal  diges4ve  track  

• Common  arthropods  include  arachnids,  crustaceans  and  their  rela4ves  

Crustacea   Malacostraca   Decapoda  (crabs,  shrimp,  lobsters)  

Isopoda  (pillbugs,  sowbugs)  

Hexapoda   Entognatha   Collembolla  (springtails)  

Insecta   Thysanura  (silverfish)  

Odonata  (damselflies,  dragonflies)  

Orthoptera  (grasshoppers,  crickets)  

Hemiptera  (bugs,  aphids,  scales)  

Coleoptera  (beetles,  weevils)  

Lepidoptera  (moths,  buNerflies)  

Chelicerata   Arachnida   Araneae  (spiders)  

Scorpiones  (scorpions)    

Acari  (4cks,  mites,  chiggers)  

Myriapoda   Chilopoda   (Cen4pedes)  Diplopoda   (Milipedes)  

Phylum

 Arthrop

oda  

Myriapoda: Chilopoda

Myriapoda: Diplopoda Crustacea: Isopoda Phylum: Mollusca

Entognatha: Collembola

Arachnida: Scorpiones

Class  Arachnida  

• Mites,  4cks,  spiders  and  scorpions  

• Two  body  regions:  cephalothorax  and  abdomen  

• Four  pairs  of  legs  • Most  are  predators  but  some  are  pests  

 

• Approximately  1  million  species  of  insects  have  been  named  

• Beetles  (Coleoptera),  flies  (Diptera)  and  wasps  &  bees  (Hymenoptera)  are  the  most  diverse  groups  

• High  insect  diversity  makes  their  iden4fica4on/  classifica4on  complex  

Insect  Diversity    

Taxonomic  Classifica4on  •  Insects  are  classified  into  groups  called:  Orders  

•  Orders  are  subdivided  into  smaller  groups  known  as  Families,  genera  and  species  Example:  Tea  scale    Order:  Hemiptera    Family:  Diaspididae    Genus:  Fiorinia    Species:  theae  

North  American  Insect  Orders      1.  Microcoryphia  (bristletails)    2.  Thysanura  (silverfish)  3.  Ephemeroptera  (mayflies)  4.  Odonata  (dragonflies)  5.  BlaFodea  (cockroaches)  6.  Isoptera  (termites)  7.  Mantodea  (manKds)  8.  GrylloblaFodea  (rockcrawlers)  9.  Dermaptera  (earwigs)  10. Plecoptera  (stoneflies)  11. Orthoptera  (crickets)  12. Phasmida  (sKck  insects)  13. Embioptera  (webspiners)  14. Zoraptera  (angel  insects)  15. Psocoptera  (barklice)  

16. Phthiraptera  (barklice)  17. Hemiptera  (bugs,  scales)  18. Thysanoptera  (thrips)  19. Megaloptera  (dobsonflies)  20. Rhaphidiopera  (snakeflies)  21. Neuroptera  (lacewings)  22. Strepsiptera  (twisted-­‐wings)  23. Coleoptera  (beetles)  24. Mecoptera  (scorpionflies)  25. Siphonaptera  (fleas)  26. Diptera  (flies)  27. Trichoptera  (caddisflies)  28. Lepidoptera  (buFerflies)  29. Hymenoptera  (bees)  

Insect  Anatomy  

•  Head,  thorax  &  abdomen  

•  Antennae    •  Adults  may  have  one  or  two  pairs  of  wings  

•  Three  pairs  of  legs  aNached  to  thorax  

Insect  Physiology  

•  Insects  breath  through  spiracles;  valves  on  the  side  of  their  body  

• Open  circulatory  system  

• Flight  is  accomplished  by  vibra4ng-­‐resona4ng  mechanism  

•  Insects  are  poikilothermic:  temperature  changes  with  ambient  

Insect  Development  

• Metamorphosis  

• Stages  may  show  differences  in  shape,  diet  and  habitat  

• Highly  developed  insects  experience  complex  metamorphosis  

Ametamorphosis  

Simple,  gradual  metamorphosis  

Complete  metamorphosis  

Metamorphosis  • Anamorphosis  (young  have  less  abdominal  segments;  very  rare)  

• Ametamorphosis  (ametabolous  insects;  con4nue  mol4ng  aaer  adult  stage)  

• Simple  metamorphosis    – Gradual  (paurometabolous;  young  [nymphs]  resemble  wingless  adults;  in  same  habitat)  

–  Incomplete  (hemimetabolous;  young  [niad]  acua4c  may  not  resemble  adult)  

• Complete  metamorphosis  (holometabolous;  pupal  stage;  may  not  be  in  same  habitat)  

• Hypermetamorphosis  (1st  instar  triangulin)  

Types  of  Larvae  

Eruciform  Elateriform  

Scarabaeiform  

Campodeiform  

Vermiform  

Grub  

Maggot  

Caterpillar  

Grub  

Common  Insect  Orders  

• Orthoptera:  grasshoppers,  crickets  • Hemiptera:  true  bugs,  scales,  aphids,  whiteflies  

• Thysanoptera:  thrips  • Coleoptera:  beetles  and  weevils  • Lepidoptera:  moths  and  buNerflies  • Diptera:  flies  and  mosquitoes  • Hymenoptera:  wasps,  bees,  ants  

Orthoptera:  grasshoppers  &  crickets  

• Outer  wings  leathery  (tegmina),  inner  wings  membranous  and  fan-­‐shaped    

• All  stages  have  chewing  mouthparts  

• Undergo  simple  metamorphosis;  wingless  nymphs  resemble  adults  

• Enlarged  hind  legs  for  jumping  

Grasshoppers,  Crickets  and  Katydids  

Tree cricket

False katydid

Field cricket

Cave cricket Differential grasshopper Rainbow grasshopper

Hemiptera:  Auchenorrhyncha  and  Stenorryncha;  leahoppers,  aphids,  scales  and  whiteflies  

• Soa  bodied  insects  with  sucking  mouthparts  

• Some  adult  forms  lack  wings  

• Undergo  simple  metamorphosis  

• Most  excrete  honeydew  

• Can  transmit  plant  diseases  

Scales,  Aphids,  Whiteflies,  Mealybugs,  Leahoppers  and  Cicadas  

Citrus mealybug

Silverleaf whitefly Green peach aphid

Wax scale

Cicadas

Sharpshooter

Hemiptera:  Heteroptera;  true  bugs  • Outer  wings  thickened  or  leathery  at  base  and  membranous  at  4p  (hemelytra),  inner  wings  membranous  

• Piercing  and  sucking  mouthparts  

• Undergo  simple  metamorphosis  

• Triangular  plate  (scutellum)  between  thorax  and  abdomen  on  the  back  

The  True  bugs!!  

Water strider

Giant water bug

Leaffooted bug Bigeyed bug

Spined soldier bug Azalea lacebug

Thysanoptera:  thrips  

•  Intermediate  metamorphosis  • Narrow  wings  with  a  fringe  of  long  hairs  

• Rasping-­‐sucking  mouthparts  • Less  than  ¼  inch  • Some  are  predators  but  most  feed  on  plants  

Coleoptera:  beetles  &  weevils  

• Hardened  outer  wings  (elytra)  and  membranous  inner  wings  

• Chewing  mouthparts,  complete  metamorphosis  

• Larvae  (scarabaeiform,  campodeiform,  elateriform,  grubs)  have  hardened  head  capsule  and  3  pairs  of  legs  on  thorax    

• Most  diverse  group  of  insects  

Beetles  &  Weevils  

Cucumber beetle

Boll weevil

White grubs

Tiger beetle Lady beetle larva

Lady beetle adult

Lepidoptera:  moths  &    buNerflies  • Four  well  developed  membranous  wings  covered  with  scales  

• Larvae  have  chewing  mouthparts,  adults  have  coiled  sucking  tube  

• Undergo  complete  metamorphosis  • Larvae  (eruciform,  caterpillars)  have  3  pairs  of  true  legs  on  thorax  and  variable  number  of  prolegs  on  abdomen  

Moths  &  BuNerflies  

Cabbage looper

Bag worm Yellowstriped armyworm Sugarcane borer

Tent caterpillar

Monarch butterfly

Diptera:  flies  &  mosquitoes  

• Adults  have  one  pair  of  wings  

• Sponging  or  piercing  (adults),  mouth  hooks  or  chewing  (larvae)  mouthparts  

• Undergo  complete  metamorphosis  

• Most  larvae  (vermiform;  maggots)  don’t  have  legs  or  head  capsule  

Flies  &  mosquitoes  

Tachinid fly

Horse fly Fungus gnats

Love bugs Med fly

Yellow fever mosquito

Hymenoptera:  bees,  wasps,  ants  

•  Adults  have  two  pairs  of  membranous  wings  

•  Most  have  chewing  mouthparts  

•  Undergo  complete  metamorphosis  

•  Social  wasps  and  bees  (may  s4ng)  and  solitary  wasps  (predators  and  parasitoids)  

•  Larva  (eruciform,  grubs)  lack  legs  (except  sawflies)  

Bees,  wasps  and  ants  

Carpenter bee

Paper wasp

Aphelinid wasp

Sawfly larvae

Mud dauber

Red imported fire ant

Causes  of  Injury  to  Foliage  

• Physical  damage  (breakage,  sunburn)  

• Plant  diseases  (viruses,  fungi,  bacteria)  • Arthropod  pests  (sow  bugs,  pill  bugs,  millipedes,  insects,  mites)  

• Slugs  and  snails  • Vertebrates  (rabbits,  squirrels,  deer,  etc.)  

Damage  Caused  by  Arthropods  

• Direct  damage:  – Removal  of  plant  nutrients  – Induc4on  of  plant  disorders  

•  Indirect  damage:  – Honey  dew  secre4on  – Disease  transmission  – Reduc4on  of  aesthe4c  quality  

Proper  Iden4fica4on  is  Key  

• Not  all  insects  are  pests  (only  5%  of  all)  •  Informa4on  retrieval  and  communica4on  • Save  specimens  for  reference  

Insect  Iden4fica4on  

• Differences  in  body  parts  and  general  anatomy  (insect  families)  

• Type  of  damage  they  cause  (borers,  girdles,  leaf  miners)  

• Feeding  mechanisms  or  mouthparts  (chewing,  sucking,  intermediate)  

Insects may be categorized by:

Pest  diagnosis  based  on  

feeding  damage  

• Chewing  • Sucking  • Intermediate  

Chewing  Mouth  Parts  

• Caterpillars  • Sawfly  larvae  • Beetles  &  grubs  • Grasshoppers  •  (slugs  &  snails)  

Cabbage  looper  development    

Early  detec4on:    • Minimizes  feeding  damage  

• Facilitates  control  

Early instar

Late instar

Signs  of  chewing:  Silk  and  Frass  

Genista  caterpillar  on  Texas  Mountain  Laurel    

Fall  Webworms  and  Tent  Caterpillars  

Physical  /  mechanical  control  is  best  control  alterna4ve  

Bagworms  

•  Frequent  removal  of  bags  •  Timing  of  applica4on  •  Use  of  Bt  products  like  Dipel®    

Pest management:

•  Life  spent  in  silken  ‘bag’  

•  Females  wingless  •  Eggs  emerge  mid-­‐late  May  

TwelvespoNed  Cucumber  Beetle  

• Plants  tolerate  defolia4on  

• Damage  is  only  caused  during  fruit  development  

• Only  large  popula4ons  require  ac4on  

Flea  Beetles  

• Plants  can  tolerate  defolia4on  • Aesthe4c  damage?  

White  grubs  

Larva

Adult Treatment  not  required  for  less  than  3-­‐  5  grubs  per  a2    

Identification

Snout  Weevils  Weevils  have  chewing  mouth  parts  

Grasshoppers  and  Crickets  

•  Behavior  depends  on  density  • May  feed  on  many  plants  • Many  species  in  Texas  • May  move  large  distances  

Leafcurng  Bees  

Do not feed on leaves but use them to build nest

Symptoms  of  Chewing  Insects  

• Pieces  &  parts  of  leaves  missing,  o_en  in  characterisKc  paFerns  

• Silk  associated  with  damage  indicates  caterpillar  presence  

• Excrement  underneath  damage  can  indicate  insect  group  present  

• Brown  edges  around  damage  indicates  older  damage  

Sucking  Mouth  Parts  

•  True  bugs  •  Aphids  &  mealybugs  • Whitefly  &  scales  

Yucca  bug  and  damage  

Lace  Bugs  and  damage  

Note frass specks

Leaf  footed  &  Squash  bugs  

Leaf footed bug

Squash bug

Whiteflies,  Scales,  Mealybugs  &  Aphids  

•  Honeydew  or  sooty  mold  indicates  presence  • May  leave  cast  skins  on  leaves  •  Rapid  populaKon  growth  (outbreak)  •  Can  quickly  become  resistant  to  insecKcides  

Symptoms  of  Sucking  Insects  

• Spodng,  discoloraKon  or  death  of  leaf  Kssue  can  be  yellow  or  reddish  to  brown  

• Honey  dew  and  sooty  mold  on  leaves  under  infestaKon  indicate  presence    

• Cast  skins  on  underside  of  leaf  indicates  developing  populaKon  

Intermediate:  Thrips  

•  Some  feed  on  pollen  inside  developing  flowers  

•  Common  in  Spring,  colonize  gardens  from  wild  flowers  

•  Specks  of  frass  are  common  when  feeding  on  foliage  

•  Transmit  viral  diseases;  may  become  resistant  

Spider  Mites  

•  SKppling,  spodng,  “bronzing”,  close  to  the  midrib  

•  Eggs  clear  &  spherical,  cast  skins  on  underside  of  leaves  

•  Heavily  infested  plant  covered  in  silk  

•  Beneficial  mites  much  ‘faster’  than  pest  

Other  types  of  insect  damage  •  Leaf  mines  by  maggots,  beetle  larvae  or  caterpillars  

•  Teasing  apart  of  plant  4ssue  by  root  maggots  

•  Galls  and  deformed  plant  parts  by  cynipid  wasps,  psyllids,  some  thrips  

•  Egg-­‐laying  damage  by  cicadas,  thorn  bugs  (plant  hoppers)  

Gall-­‐Forming  Insects  and  Mites  

Cynipid  wasp  galls   Fly (top) and mite galls

Drees,  B.M.  &  J.  A.  Jackman.  1998  

Evans,  A.V.  2007  

Wagner,  D.L.  2005  

Resources  (field  guides)