Aquatic Insects of Ohio
Immatures and Adults
1. Wings or wingpads present, forewings sometimes hard and shell-like, concealing hind wings; legs present (Fig. 1.1). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Wings or wing pads entirely absent; legs present or absent . . . . . . . . . . . . . . . . . . . . . . 27
2. Wings fully developed, usually conspicuous and movable (Fig. 1.2). . . . . . . . . . . . . . . . . . 3
Wings developing in fixed wing pads, Nymphs and pupae . . . . . . . . . . . . . . . . . . . . . . . 15
3. Forewings leathery or hard, at least in the basal (nearest the body) half. . . . . . . . . . . . . . 4
Wings entirely membranous. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Chewing mothparts, mandibles visible . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Sucking mouthparts united in a jointed beak, mandibles concealed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hemiptera (True Bugs)
5. Forewings leathery, veins distinct; femora of hind legs greatly enlarged, suited for jumping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Orthoptera (Grasshoppers and Crickets; not truely aquatic, may be semiaquatic but are not covered on this webpage)
Forewings hard (called elytra), veins indistinct; hind legs suited for walking or swimming. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Coleoptera (Water Beetles)
6. One pair of wings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Two pairs of wings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7. Abdomen ending in 2 or 3 long filaments; mouthparts inconspicuous; thorax without halteres. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ephemeroptera (Mayflies, in part)
Abdomen without conspicuous filaments; mouthparts well developed, forming a proboscis; thorax with halteres. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diptera (Flies)
8. Wings covered with scales or hairs, obscuring venation . . . . . . . . . . . . . . . . . . . . . . . . . 9
Wings bare or with minute hairs, venation clearly visible. . . . . . . . . . . . . . . . . . . . . . . . . 10
9. Wings with scales; mouthparts usually fitted witha coiled sucking tube. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lepidoptera (water moths)
Wings with hairs; mouthparts without a coiled sucking tube. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . Trichoptera (caddisflies)
10. Antennae short, bristlelike, and inconspicuous. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Antennae of various shapes, conspicuous, not bristlelike. . . . . . . . . .. . . . . . . . . . . . . . . 12
11. Abdomen ending in 2 or 3 long filaments; hind wings much smaller than forewings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ephemeroptera (Mayflies, in part)
Abdomen without long filaments; wings about equal in size. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Odonata (Dragonflies and Damselflies)
12. Tarsi 2- or 3-segmented; abdomen ending with 2 conspicuous cerci (single or multi- segmented. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Plecoptera (Stoneflies)
Tarsi 5-segmented (except a few Hymenoptera [ants, bees and wasps] with 3 segments; abdomen without conspicuous appendages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
13. Abdomen broadly joined to thorax; front margin of forewing in basal half with many small veins perpendicular to edge; wings with more than 20 closed cells. . . . . . . . . . . . . . . . 14
Abdomen with narrow constriction at junction with the thorax; marginal veins in basal half of forewing parallel to leading edge; wings with fewer than 20 closed cells; aquatic forms are very small, usually less than 3 mm long. . . . . . . . . . . . . . . . Hymenoptera (ants, bees and wasps). A few may be semiaquatic but are not covered on this webpage)
14. Hindwings folded or pleated lengthwise. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Megaloptera (Dobsonflies and Alderflies)
Hindwings not folded. . . . . . . . . . . . . . . . . . . . . . . . Neuroptera (Aquatic Lacewings)
15. Active insects with legs freely movable; not in cocoons or capsule-like cases. Nymphs. . . 16
Usually inactive insects, "mummy-like" with appendages drawn up and free or capsule-like cases or puparia. Pupae. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
16. Chewing mouthparts with mandibles distinct. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Sucking mouthparts united in a jointed beak with mandibles cooncealed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hemiptera (True Bugs)
17. Hind legs suited for jumping hind femora greatly enlarged; abdomen without long cerci; found in moist places and only temprorarily in water. . . Orthoptera (Grass hoppers and Crickets; not truely aquatic, may be semiaquatic but are not covered on this webpage)
Hind legs suitable for crawling, hind femora not greatly enlarged, approximately the same size as front and middle femora; abdoment with or without conspicuous terminal appendages; usuallly submerged, truely aquatic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
18. Labium (lower lip) masklike, extendable inot a scooplike structure longer than head. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (Odonata, Dragonflies and Damselflies)
Labium normal, smaller than head, not larg and masklike. . . . . . . . . . . . . . . . . . . . . . 19
19. Tarsi with one claw; abdomen ending in three long filaments, less commonly with 2 filaments; gills located on sides of abdomen, may be plate-like, filamentous, or feathery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ephemeroptera (Mayflies)
Tarsi with 2 claws; abdomen ending in only 2 filaments; gills present, fingerlike and located at base of mouthparts (inconspicuous), head or legs, or on thorax or abdomen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Plecoptera (Stoneflies)
20. Appendages free, distinct, not fused to body (termed exarate pupae). . . . . . . . . . . . . 21
Appendages fused to body or concealed in hardened capsule (termed obtect and coarctate pupae, respectively). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
21. Abdomen broadly joined to thorax. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Abdomen with constriction where joined to thorax. . . . . . . . Hymenoptera (ants, bees and wasps). A few may be semiaquatic but are not covered on this webpage)
22. One pair of wing pads. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diptera (Flies)
Two pairs of wing pads. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
23. Pads of forewings thickened; antennae usually 11-segmented or less. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Coleoptera (Water Beetles)
Pads of forewings not thickened; antennae of 12 or more segments. . . . . . . . . . . . . . 24
24. Mandibles stout, not crossing each other; pupae terrestrial (near water's edge), not normally submerged. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Mandibles curved, projecting forward and ususally crossing each other; pupae usually submerged in water (may be in damp areas of overhanging stream banks); always in cases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Trichoptera (Caddisflies)
25. Smaller, 10 mm or less in length; pupae in double-walled, meshlike cocoons in sheltered places. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neuroptera (Water Lacewings)
Larger, 12 mm or more; pupae in chambers in soil or rotten wood without cocoons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Megaloptera (Dobsonflies & Alderflies)
26. Appendages visable on surface of pupa; without obvious brathing tubes or gills; two pairs of wing pads present(hind wings mostly concealed beneath forewings). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lepidoptera (Water Moths)
Appendages visible or entirely concealed in barrel-shaped capsule; if appendages visible then usually with projecting respiratory organs or paired, dorsal, prothoracic breathing tubes; sometimes with gills at the abdominal tip; one pair of wing pads. . . . . . . . . Diptera (Flies)
27. Abdomen with 6 or fewer segments and with a ventral tube; minute, 5 mm or less. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Collembola (Springtails) We do not carry classification further with this group.
Abdomen with more than 6 segments and without a ventral tube; ususally larger than 5 mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
28. Three pairs of jointed legs present on thorax. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
True legs absent; fleshy, leglike protuberances or prolegs may be present on thorax but fewer than three pairs and not jointed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
29. Middle and hind legs long and slender, extending considerably beyond the abdomen; compound eyes presents (wingless Gerridae). . . . . . . . . . . . . . Hemiptera (True Bugs)
Legs not longer than the abdomen; compound eyes absent. . . . . . . . . . . . . . . . . . . . 30
30. Abdomen with at least two pairs of ventral, fleshy, leglike protuberances tipped with tiny hooks (prolegs with crochets). . . . . . . . . . . . . . . . . . . . . Lepidoptera (Water Moths)
Abdomen without leglike protuberances, or, if present, not tipped with tiny hooks. . . . 31
31. Last abdominal segment with lateral appendages bearing hooks (anal hooks), antennae 1-segmented, inconspicuous; gills, if present, seldom confined to lateral margins of body; larvae free-living or in cases made of sand grains and/or bits of plant matter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Trichoptera (Caddisflies)
Last abdominal segment without anal hooks; or, if anal hooks present, antannae of more than 1 segment, and gill insertions lateral. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
32. Mandibles and maxillae united at each side to form long, straight or slightly recurved, threadlike suctorial tubes; laterally inserted, segmented gills folded beneath abdomen; small, 10 mm or less, and found in or on freshwater sponges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neuroptera (Aquatic Lacewings)
Mandibles not united with maxillae; if mandibles suctorial, then strongly curved; gills seldom segmented and not folded beneath abdomen; not associated with sponges. . . . . . . . . . . 33
33. Abdomen with 7 or 8 pairs of lateral filaments or gills, arranged 1 pair on each segment; segment 9 with hooked lateral appendages (anal hooks) or a single, medial, caudal filament. . . . . . . . . . . . . . . . . . . . . . . . . . . Megaloptera (Dobsonflies & Alderflies)
Abdomen usually without lateral gills; if segmental gills present, then (a) anal hooks absent, or (b) segment 10 with 4 gills, or (c) caudal appendages paired or absent, never single. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . Coleoptera (Water Beetles)
34. Head capsule distinct, partly or entirely hardened and usally pigmented, but may be deeply withdrawn in prothorax. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Head capsule absent, not distinct, hardened, or pigmented often consisting of a few pale rods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
35. Posterior end of body with at least one or a combination of gills, hair brushes, a sucker, or breathing tube. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diptera (Flies) in part
Posterior end of body simple or with small processes or isolated hairs, but without gills, brushes, suckers or breathing tubes. . . . . (Curculionidae) Coleoptera (Water Beetles)
36. Body usually 5 mm or larger, elongate, somewhat cylindrical, spindle-shaped or maggotlike; mouthparts may be reduced to a pair of retractile mouth hooks that move vertically. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diptera (Flies) in part
Body usually 5 mm or less; mouthparts may be reduced to a pair of opposable, acute mandibles that move horizontally; parasitoids on or inside insect hosts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hymenoptera (ants, bees and wasps). A few may be semiaquatic but are not covered on this webpage)
