Key to the Orders of Aquatic Hexapoda (Insects and Collembola) of Michigan

Key to the Orders of Aquatic Hexapoda (Insects and Collembola) of Michigan

1a. Thorax without segmented legs (except pupae) 2

1b. Thorax with 3 pairs of segmented legs 3
2a (1a). Mummy-like, in a case, often silk-cemented and containing vegetable or mineral matter

pupae (not keyed)

2b. Not in a case; mobile larvae, mostly with prolegs or pseudopods on one or more segments

Diptera
3a (1b). With large, functional wings 4

3b. Wingless, or with developing wings (wingpads) or brachypterous wings 5

4b. Mesothoracic wings hard, shell-like, meeting along middorsal line; chewing mouthparts

4c. Mesothoracic wings hardened in basal half only, overlapping along middorsal line (except in Pleidae); sucking mouthparts, formed into a broad or narrow tube Heteroptera adults (in part)

5b. Thoracic legs 5-segmented; abdomen with  6 segments; abdominal furcula absent 6

6b. Terminal filaments absent, or consisting of < 10 segments 8

7b. Tarsal claws double; middle abdominal segments without gills; two terminal filaments

8b. Labium not modified as above, with chewing or sucking mouthparts 9

9b. Chewing mouthparts, not formed into a narrow tube 11

10b. Free-living; mesotarsi with 2 claws Heteroptera adults and larvae

11b. Abdomen without ventral prolegs, except on terminal segment 12

12b. Antennae elongate, with three or more segments 13

13b. With long lateral filaments 14

14b. Each tarsus with 2 claws, and abdomen terminating in a single slender filament or abdomen terminating with 2 prolegs, each with 2 hooks Megaloptera larvae

Wing Life Jointed Abdomen No.

Odonata Y Y 10-20

Heteroptera Y Y 10-20

Holometabolous Megaloptera Y N 5

Neuroptera Y N 3

Trichoptera Y N 4-5

Lepidoptera usually N 5-6

Coleoptera Y sometimes 5

Diptera N N 4

Key to the Michigan Families of Adult Collembola - Springtails

1a. Body somewhat globular; thorax and abdomen indistinctly segmented Smithuridae

1b. Body elongate; thorax and abdomen distinctly segmented 2
2a (1b). Mouthparts directly downward; furcula present, and forks distinctly converge

Poduridae, Podura aquatica

2b. Mouthparts directed forward; furcula absent or forks do not distinctly converge

Key to the Michigan Families of Larval Ephemeroptera - Mayflies

1a. Mandibles with large forward-projecting tusks; all gills on abdominal segments 2-7 with fringed margins, projecting dorsally or laterally 2

1b. Mandibles without tusks; fringed gills absent or projecting ventrolaterally 4
2a (1a). Gills lateral, projecting from sides of abdomen; foretibiae slender, sub-cylindrical

Potamanthidae

2b. Gills dorsal, curving up over abdomen; foretibiae fossorial, expanded in width 3

3b. Apex of metatibia projected into an acute point ventrally; mandible tusks curved upward or outward apically Ephemeridae

4b. Mesonotum not modified into a carapace; gills exposed 5

5b. Head and pronotum without pads of long, dark setae; without ventrolateral fringed gills 6

6b. Gills present on abdominal segments 1-7 or 2-7 7

7b. Gills on abdominal segment 2 similar to other gills 9

8b. Operculate gills on abdominal segment 2 sub-quadrate and overlapping mesally; succeeding gills with fringed margins Caenidae

9b. Head not flattened; antennae and eyes lateral; gills not as above 11

10b. Gills without such a finger-like projection; tarsal claws normal Heptageniidae

11b. Claws on all tarsi similar in length and structure 13

12b. Protarsal claw bifid; no spinose pad on procoxa Metretopodidae

13b. Prothoracic leg without dense row of setae along inner surface 15

14b. Gills on abdominal segments 2-7 small, lateral, lanceolate, with posterior fringe; gill on segment 1 large, fibrilliform, projecting between metacoxae Oligoneuriidae

15b. Gills formed as single or double lamellae, sometimes with ventral fibrilliform tuft 16

16b. Abdominal segments 8 and 9 without such spines; if weak spines are present, antennal > 2x width of head Baetidae

17b. Without such spines 18

18b. Gills with well-developed tracheation; maxilla without pectinate spines Siphlonuridae

Key to the Michigan Families of Larval Odonata – Dragon- and Damselflies

1a. Body slender, head wider than thorax and abdomen ; abdomen ending with three caudal lamellae (gills are fragile, often falling off with rough or frequent handling of live or preserved specimens) Zygoptera, 2

1b. Body stout, head usually narrower than thorax and abdomen ; no large caudal lamellae, rather body ending in 3 stiff, pointed valves, separated by pointed cerci Anisoptera, 4
2a (1a). Antennal segment 1 elongate, as long or longer than remaining segments ; prementum with prominent cleft Calopterygidae

2b. Antennal segment 1 short, distinctly less than length of remaining segments 3

3b. Labium shorter, in folded position never reaching the middle coxae, not markedly narrowed in basal half Coenagrionidae

4b. Mentum spoon-shaped, usually with premental and always with palpal setae 7

5b. Antennae 6- and 7-segmented ; fore and middle tarsi 3-segmented ; ligula with a median cleft 6

8b. Head without frontal horn positioned between antennae ; metafemur not reaching apex of abdominal segment 8 ; metasternum without median tubercle 9

9b. Distal edge of lateral lobe of labium generally with crenations less than one-fourth as wide, or obsolete ; cerci usually less than one-half as long as epiproct ; abdomen distally more tapered Libellulidae (in part)

10b. Lateral spine of abdominal segment 8 as long as middorsal length of abdominal segment 9, or longer Libellulidae, genus Pantala

Key to the Michigan Families of Larval Plecoptera – Stoneflies

1a. Labial glossa and paraglossa subequal 2

1b. Labial paraglossa produced much further than the glossa 6
2a (1a). Large tufted gills on the sides of abdominal segments 1 and 2 Pteronarcyidae

2b. No such gills 3

3b. Thorax and abdomen about equal in length; wing pads roughly parallel 5

4b. Tarsomere 2 much shorter than 1 Nemouridae

5b. Mesothoracic wing pads subequally separated or absent, or metathoracic wing pad truncated ; terga and sterna of abdominal segments 1-9 divided by a membranous fold ventrolaterally Capniidae

6b. Finely branched gills, if present, only on first thoracic sterna 7

7b. Margins of metathoracic wing pads nearly parallel ; cerci about 0.75x the length of abdomen ; apical segment of labial palp basally much thinner as preceding segment (rare in MI)

Key to the Michigan Families of Larval Trichoptera – Caddisflies

1a. Larval case of sand grains resembling a snail case ; anal claw with comb of teeth, not hook-shaped Helicopsychidae

1c. Larval case and anal claw not as above 2
2a (1b). All three thoracic segments with dorsal sclerotized plates 3

2b. Metanotum, and sometimes the mesonotum, entirely membranous or largely so but with several pairs of smaller sclerites 4

3b. Abdomen lacking ventrolateral gills ; anal proleg usually not projecting freely from abdomen, claw always small and without setal brush ; small (<6 mm), construct purse- or barrel-shaped portable cases, or silken domes fastened to rocks Hydroptilidae

4b. Antennae of normal length, < 3x as long as wide and usually no more than an inconspicuous stub ; mesonotum never with pair of dark curved lines as above 5

5b. Mesonotum largely covered by sclerotized plates, variously subdivided and usually pigmented; pronotum sometimes with prominent anterolateral lobe 11

6b. Abdominal segment 9 without dorsal sclerotized plate 8

7b. Larvae construct tortoise-like portable case of rock fragments ; without prosternal horn; basal half of anal proleg broadly joined to abdominal segment 9, anal claw with at least one dorsal accessory hook Glossosomatidae

7c. Larvae free-living without portable cases but construct fixed pupal enclosures; without prosternal horn; most of anal proleg free from abdominal segment 9, anal claw without dorsal accessory hook, although secondary lateral claw may be present Rhyacophilidae
8a (6b). Labrum membranous and T-shaped , often withdrawn from view in preserved specimens; larvae construct fixed sack-like nets of silk Philopotamidae

8b. Labrum sclerotized, rounded and articulated in normal way 9

9b. Trochantin of prothoracic leg with apex acute, fused completely with episternum without separating suture ; 10

10b. Tarsi of all legs normal, not flattened, tibiae longer than tarsi ; larvae construct exposed funnel-shaped capture nets or flattened retreats Polycentropodidae

11b. Abdominal segment 1 always with lateral hump on each side, though not always prominent, and usually with dorsal hump ; metanotal sa1 always present, usually with prominent sclerite with at least one setae 12

12b. Mesopleuron not extended as an acute process 13

13b. Antennae not situated close to anterior margin of eye, ; dorsal hump on abdominal segment 1 almost always present 14

14b. Antennae situated close to or at anterior margin of head capsule ; prosternal horn and chloride epithelia never present 17

15b. Mesonotal plates without such emargination 16

16b. Mandibles almost always toothed ; metanotal sa1 lacking setae on membrane between sclerites, or fewer than 25 setae if present Limnephilidae

17b. Tarsal claws of hind leg not different in structure from those of other legs 18

18b. Fore trochantin smaller, apex not hook-shaped ; dorsum of anal proleg with no more than 3-5 setae posteromesad of lateral sclerite, sometimes with short spines Odontoceridae

Key to the Michigan Families of Larval Megaloptera – Dobson- and Alderflies

1a. With 7 pairs of lateral segmented abdominal appendages; a long terminal anal filament; anal prolegs absent; larvae rarely exceed 25 mm in length Sialidae

1b. With 8 pairs of lateral abdominal appendages that are not or imperfectly segmented; no terminal anal filament; anal prolegs present; mature larvae large, exceeding 30 mm

Corydalidae

Key to the Michigan Families of Adult Heteroptera – Aquatic and Semi-aquatic Bugs

Note: Lengths refer to adults, with have developed wings.

1b. Antennae as long, or longer, than head, usually plainly visible; semiaquatic 8

2b. Rostrum cylindrical or cone-shaped, distinctly 3- or 4-segmented; front tarsus not scoop-like

3
3a (2b). End of abdomen with a long, slender, rounded respiratory appendage Nepidae

3b. Apical respiratory appendages, if present, short and flat 4

4b. Eyes not protuberant; ocelli absent; metathoracic leg with natatory setae; not toad-like in appearance 5

5b. Smaller, < 16 mm in length; apical abdominal appendages absent 6

6b. Profemur elongate; body elongate or hemispherical; backswimmers 7

7b. Body elongate; larger, > 5 mm long Notonectidae

8b. Claws of all tasi at apex 10

9b. Metafemur shorter, not, or only slightly surpassing apex of abdomen Veliidae

10b. Head short and stout, eyes near posterior margin 11

11b. Wingless, or if winged, without veins in the membrane 12

12b. Tarsi 2-segmented; head with deep longitudinal ventral groove to receive rostrum; rostrum only partially visible from lateral view; legs without bristles; smaller, body length < 2.0 mm

Key to the Michigan Families of Coleoptera – Beetles

1a. Wingless Larvae, 2

1b. With well-developed, functional wings Adults, 12
2a (1a). Each tarsus with 2 claws 3

2b. Each tarsus with 1 claw 5

3b. Abdomen without lateral filaments or with only 6 pairs; without conspicuous hooks on last abdominal segment 4

4b. Urogomphi shorter than last abdominal segment; posterior half of abdomen little narrowed; legs stout, short and without natatory setae; mandibles short, adapted for chewing Noteridae

5b. Legs appearing 4-segmented; abdomen not terminating in long filaments 6

6b. Mandibles not readily visible from above 7

7b. Antenna much shorter than head and thorax combined 8

8b. Body elongate, round, or triangular in cross-section; head exposed 9

9b. Thoracic and abdominal segments rounded dorsally; without clump of large papillae ventrally

10
10a (9b). All terga rounded and pale; grub-like larva with two spines on last abdominal segment

Chrysomelidae

10b. Body elongate and sclerotized, with ventral movable operculum closing caudal chamber containing gills 11

11b. Last abdominal tergum broadly rounded; one ventral stemma below base of antenna in addition to 5 stemmata posterior to base Lutrochidae

12b. Head not formed into a beak or snout; antennae not geniculate 13

13b. One pair of eyes; meso- and metathoracic legs not extremely flattened; tarsi not folded fan-wise 14

14b. Metacoxae not expanded into large plates 15

15b. Prosternum with postcoxal process absent or short; first visible abdominal sternite extending for its entire breadth behind coxal processes 17

16b. Enlarged median metasternal keel absent; without large, curved spur at apex; scutellum concealed or exposed Dytiscidae

17b. Antenna filiform or pectinate, usually longer than maxillary palp 19

18b. Antenna with 3 segments past cupule Hydrophilidae

19b. Antenna short with pectinate club Dryopidae

Key to the Michigan Families of Larval Diptera – True Flies

1a. Mandibles moving against one another in a horizontal or oblique plane; head capsule usually completely sclerotized and fully visible, but retracted and partially sclerotized in Tipulidae

Suborder Nematocera, 2

1b. Mandibles or mouth hooks moving parallel to one another in a vertical plane

Suborder Brachycera, 13
2a (1a). Head capsule incompletely sclerotized, with longitudinal incisions of varying depths dorsolaterally, in extreme cases head reduced to several slender rods, and more or less retracted into thorax Tipulidae

2b. Head capsule complete, without longitudinal incisions and incapable of retraction within thorax 3

3b. Body with distinct constriction between head and thorax; body not appearing as above, and without ventral suctorial disks 4

4b. Without having any of the above characteristics 5

5b. Thorax segments usually distinct, thorax and abdomen about equal in diameter, or abdomen wider (except Dixidae); setae on thoracic and abdominal segments not tufted, and anal fan of terminal segment absent 7

6b. Abdominal segments without prolegs; abdomen not as above 7

7b. Prothorax without prolegs 11

8b. Head capsule without labral fans; posterior of abdomen not swollen, posterior of abdomen not as above, although anal proleg(s) bearing crochets may be present 9

9b. Without spiracles; prothoracic or anal prolegs usually paired, although a slight separation of apical spines may be present 10

10b. All body segments lacking prominent dorsal tubercles and setae Chironomidae

11a (7b). Posterior 2 abdominal segments with long filamentous processes, pairs of such processes arising laterally on the penultimate segment, dorsolaterally on the terminal segment, and from near the apex of 2 elongate cylindrical prolegs that project postero-ventrally from the terminal segment Tanyderidae

11b. Posterior 2 abdominal segments without long filamentous processes; at most, only a single anal proleg present 12

12b. Body segments usually not secondarily divided; integument smooth, shiny, and creamy white, lacking all surface features except a few setae, and sometimes a retractile anal proleg bearing a few crochets; without respiratory tubes Ceratopogonidae (in part)

Infraorder Orthorrhapha, 14

13b. External sclerotized portions of head capsule absent; head reduced to an internal cephalopharyngeal skeleton Infraorder Cyclorrhapha, 18
14a (13a). Head mostly visible, truncate in shape; body dorsoventrally flattened; margin of posterior spiracular chamber usually with long, soft setae Stratiomyidae

14b. Head vestigial or mostly retracted into thorax and elongate; body nearly circular in cross-section; spiracular chamber without long, soft setae 15

15b. Body variable; abdomen with at most 1 pair of prolegs per segment, or with creeping welts; spiracles present or absent; terminal abdominal segment with 1-2 pairs of appendages or lobes 16

16b. End of abdomen variable, but not ciliated as above, usually shorter than prolegs and reduced to fleshy lobes; abdominal segments with creeping welts or with prolegs lacking from first abdominal segment; spiracles absent or present 17

17b. Usually without spiracles, with last abdominal segment with 1-4 rounded lobes bearing apical setae, and abdominal segments bearing paired prolegs with apical crochets; if with spiracles at end of abdomen, then posterior segment with only a single lobe below spiracles, and abdominal segments with ventral creeping welts; metacephalic rods slender posteriorly in dorsal view Empididae

18b. Pharyngeal skeleton not so produced; rarely associated with pitcher plants 19

19b. Posterior spiracular plates always distinctly separated, whether mounted on a retractile respiratory tube or not 20

20b. Caudal spiracular disk without palmate hairs; if surrounded by lobes, body not wrinkled