Kwik-Key to Soil-Dwelling Invertebrates


Step A.  How many walking legs are present?
             a.  Zero . . . . . . . . . . . . . . . Go to Step NN
             b.  4-6 (2-3 pairs). . . . . . . . . . Go to Step K
             c.  8 (4 pairs). . . . . . . . . . . . Go to Step G
             d.  10-16 (5-8 pairs). . . . . . . . . Go to Step E
             e.  18 (9 pairs) . . . . . . . . . . . Go to Step D
             f.  20-24 (10-12 pairs). . . . . . . . Go to Step C
             g.  26 or more (more than 13 pairs . . Go to Step B

 

Step B.  How many legs are attached to each body segment?
             a.  2 (1 pair) . . . . . . Class Chilopoda (Centipedes)
             b.  4 (2 pairs). . . . . . Class Diplopoda (Millipedes)

 

Step C.  Are eyespots visible on each side of the head?
             a.  Yes  . . . . . . Class Chilopoda (immature centipedes)
             b.  No . . . . . . . . . . . . . . . Class Symphyla

 

Step D.  Are the antennae branched?
             a.  Yes. . . . . . . . . . . . . . . Class Pauropoda
             b.  No . . . . . . . Class Chilopoda (immature centipedes)

 

Step E.  Are the legs at the front of the body notably DIFFERENT in
         shape and structure from legs at the back of the body?
             a.  Yes. . . . . . . . . . . . . . . . Go to Step P
             b.  No . . . . . . . . . . . . . . . . Go to Step F

 

Step F.  Are gill openings present ventrally on the last five body
         segments?
             a.  Yes. . . . Crustacea, Order Isopoda (pillbugs and sowbugs)
             b.  No . . . . . . . Class Chilopoda (immature centipedes)

 

Step G.  Are the last pair of legs different in structure from the others?
             a.  Yes. . . . . . . . . . . . . . . . Go to Step P
             b.  No . . . . . . . . . . . . . . . . Go to Step H

 

Step H.  Is the body divided into two parts, with a distinct constriction
         behind the last pair of legs?
             a.  Yes. . . . . . . . . . . . . Order Araneae (spiders)
             b.  No . . . . . . . . . . . . . . . . Go to Step I

 

Step I.  Are the first pair of appendages (pedipalps) enlarged as pincers?
             a.  Yes. . . . . . Order Pseudoscorpiones (Pseudoscorpions)
             b.  No . . . . . . . . . . . . . . . . Go to Step J

 

Step J.  Are the legs more than twice as long as the body?
             a.  Yes. . . . . . . . . . . Order Opiliones (Harvestmen)
             b.  No . . . . . . . . . . . Order Acarina (mites and ticks)

 

Step K.  Look for evidence of wings on the thorax.
             a.  One pair of wings present. . . . . Go to Step FF
             b.  Two pairs of wings present . . . . Go to Step HH
             c.  Hardened wing covers present . . . Go to Step EE
             d.  Short wing pads present. . . . . . Go to Step R
             e.  No visible evidence of wings . . . Go to Step L

 

Step L.  Are visual organs present on the head?
             a.  Compound eyes present. . . . . . . Go to Step R
             b.  Only simple eyes (ocelli). . . . . Go to Step P
             c.  No compound eyes or ocelli . . . . Go to Step M

 

Step M.  How many segments are present in the antenna?
             a.  Antennae apparently absent . . . . Go to Step N
             b.  4-8 segments . . . . . . . Order Collembola (springtails)
             c.  More than 8 segments . . . . . . . Go to Step O

 

Step N.  Is the head distinct and the body elongate?
             a.  Yes. . . . . . . . . . . . . Order Protura (proturans)
             b.  No . . . . . . . . Order Acarina (larval ticks and mites)

 

Step O.  Is there a pair of filaments or pincers on the end of the abdomen?
             a.  Yes. . . . . . . . . . . . . Order Diplura (diplurans)
             b.  No . . . . . . . . . . . . . Order Isoptera (termites)

 

Step P.  How many abdominal prolegs are present?
             a.  Zero . . . . . . . . . . . . . . . Go to Step R
             b.  2-10 (1-5 pairs) . . . Order Lepidoptera (moth larvae)
             c.  More than 10 (more than 5 pairs) . Go to Step Q

 

Step Q.  Abdominal prolegs are best described as:
             a.  Rounded and fleshy . . . . Order Hymenoptera (sawflies)
             b.  Slender and pointed. . . . Order Mecoptera (scorpionflies)

 

Step R.  How many segments are present in the antennae?
             a.  Less than 8. . . . . . . . . . . . . . Go to Step S
             b.  8 or more. . . . . . . . . . . . . . . Go to Step X

 

Step S.  The mouthparts are best described as:
             a.  Piercing sucking (slender proboscis) . Go to Step W
             b.  Mandibulate (2-4 palps visible). . . . Go to Step U
             c.  Hidden within the head . . . . . . . . Go to Step T

 

Step T.  Which of these structures is present?
             a.  Forked springing organ (furcula) . . . Order Collembola
             b.  Collophore near hind legs. . . . . . . Order Collembola
             c.  Abdomen with six segments. . . . . . . Order Collembola
             d.  Abdomen with more than six segments. . Order Thysanoptera
             e.  Spindle-shaped body. . . . . . . . . . Order Thysanoptera

 

Step U.  Are there 1 or 2 small nodes (segments) between thorax and abdomen?
             a.  Yes. . . . . . . . . . . . . . Order Hymenoptera (ants)
             b.  No . . . . . . . . . . . . . . . . . . Go to Step V

 

Step V.  Are the mandibles and maxillae as long as the head and sickle-shaped;
         also one pair of stout hooks near the anus?
             a.  Yes. . . . . . . . . . . . . . . . . Order Neuroptera
             b.  No . . . . . . . . . . . . . . . . . Order Coleoptera

 

Step W.  Where does the proboscis attach to the head?
             a.  Near the front . . . . Order Hemiptera - Heteroptera
             b.  Near the back. . . . . Order Hemiptera - Homoptera

 

Step X.  What structures are present on the end of the abdomen?
             a.  2 or 3 long, slender filaments . . . Order Thysanura
             b.  One pair of heavy pincers. . . . . . Order Dermaptera
             c.  Short cerci, spines, or bare . . . . Go to Step Y

 

Step Y.  Is the first segment of the thorax significantly narrower than the
         head and abdomen -- forming a slender "neck"?
             a.  Yes. . . . . . . . . . . . . . . . . Go to Step Z
             b.  No . . . . . . . . . . . . . . . . . Go to Step AA

 

Step Z.  Do the mouthparts face forward or downward from the head?
             a.  Forward. . . . . . . . . . . . Order Isoptera (termites)
             b.  Downward . . . . . . . . . . . Order Psocoptera (barklice)

 

Step AA.  Are halteres (knobs or clubs) present on the thorax?
             a.  Yes. . . . . . . . . . . . . . Order Diptera (flies)
             b.  No . . . . . . . . . . . . . . . . . Go to Step BB

 

Step BB.  Are there 1 or 2 small nodes (segments) between the thorax and abdomen?
             a.  Yes. . . . . . . . . . . . . Order Hymenoptera (ants)
             b.  No . . . . . . . . . . . . . . . . . Go to Step CC

 

Step CC.  Are the hind legs adapted for jumping?
             a.  Yes. . . . . . . . . . . . . . . . Order Orthoptera
             b.  No . . . . . . . . . . . . . . . . . Go to Step DD

 

Step DD.  How long are the antennae?
             a.  Nearly as long as the body . . Order Dictyoptera (roaches)
             b.  Less than half body length . . Order Coleoptera

 

Step EE.  Does the abdomen end in a pair of stout pincers?
             a.  Yes. . . . . . . . . . . . . . Order Dermaptera (earwigs)
             b.  No . . . . . . . . . . . . . . Order Coleoptera (beetles)

 

Step FF.  Are halteres (knobs or clubs) present on the thorax?
             a.  Yes. . . . . . . . . . . . . . Order Diptera (flies)
             b.  No . . . . . . . . . . . . . . . . . Go to Step GG

 

Step GG.  The mouthparts are best described as:
             a.  Biting/chewing (mandibulate) . . . Order Hymenoptera
             b.  Piercing/sucking (proboscis) . Order Hemiptera - Homoptera

 

Step HH. The front wings are best described as: a. Covered with a fine dusting of scales. Order Lepidoptera b. Half membranous aand half leathery . . Order Hemiptera c. Rod-like with a long fring of hairs. . Order Thysanoptera d. Opaque and leathery in appearance. . . Go to Step JJ e. Rigid and brittle. . . . . . . . . . . Go to Step EE f. Entirely membranous. . . . . . . . . . Go to Step LL

 

Step JJ.  The mouthparts are best described as:
             a.  Piercing/sucking (proboscis) . . . . . Order Hemiptera
             b.  Biting/chewing (mandibulate) . . . . . Go to Step KK

 

Step KK.  Are the hind legs adapted for jumping?
             a.  Yes. . . . . . . . . . . . . . . . . . Order Orthoptera
             b.  No . . . . . . . . . . . . . . . . . . Order Dictyoptera

 

Step LL.  Is the first segment of the thorax significantly narrower
          than the head and abdomen -- forming a slender "neck"?
             a.  Yes. . . . . . . . . . . . . . . . . . Go to Step MM
             b.  No . . . . . . . . . . . . . . . . . . Order Hymenoptera

 

Step MM.  Do the mouthparts face forward or downward from the head?
             a.  Forward. . . . . . . . . . . . . . . . Order Isoptera
             b.  Downward . . . . . . . . . . . . . . . Order Psocoptera

 

Step NN.  Is the body divided into segments?
             a.  Yes. . . . . . . . . . . . . . . . . . Go to Step PP
             b.  No . . . . . . . . . . . . . Aschelminthes (roundworms)

 

Step PP.  How many segments are visible on the body?
             a.  Less than 10 . . . . . . . . . Crustacea or Rotifera
             b.  10 to 15 . . . . . . . . . . . . . . . Go to Step QQ
             c.  More than 15 . . . . . . . . . . . . . Annelid worms

 

Step QQ.  The head and mouthparts are best described as:
             a.  Head distinct with chewing mouthparts. . . Go to Step RR
             b.  No obvious head, but mouthparts are visible . Coleoptera
             c.  No visible head or mouthparts. . . . . . . Go to Step VV

 

Step RR.  Are the last pair of spiracles larger than any others?
             a.  Yes. . . . . . . . . . . . . . . . Order Diptera (flies)
             b.  No . . . . . . . . . . . . . . . . . . . Go to Step SS

 

Step SS.  Are the head and mouthparts hard and dark-colored, contrasting with
          the appearance of the thorax?
             a.  Yes. . . . . . . . . . . . . . . . . Order Coleoptera
             b.  No . . . . . . . . . . . . . . . . . . . Go to Step TT

 

Step TT.  Is the body covered with a dense coat of hair?
             a.  Yes. . . . . . . . . . . . . . Order Siphonaptera (fleas)
             b.  No . . . . . . . . . . . . . . Order Hymenoptera

 

Step VV.  Are the last pair of spiracles larger and more obvious than the others?
             a.  Yes. . . . . . . . . . . . . . Order Diptera (flies)
             b.  No . . . . . . . . . . . . . . Order Hymenoptera

 


Return to Ground Crew or ENT 525 HomePage John R. Meyer
Last Updated:   30 December 2013 Department of Entomology
NC State University