Aquatic Insects of Michigan
by Ethan Bright, Museum of Zoology Insect Division and School of Natural Resources and Environment
University of Michigan
- Home
- Species Lists
- Coleoptera
- Diptera
- Ephemeroptera
- Acanthametropodidae
- Ameletidae
- Ametropodidae
- Arthropleidae
- Baetidae
- Baetiscidae
- Behningiidae
- Caenidae
- Ephemerellidae
- Ephemeridae
- Heptageniidae
- Isonychiidae
- Leptohyphidae
- Leptophlebiidae
- Metretopodidae
- Neoephemeridae
- Oligoneuriidae
- Palingeniidae
- Polymitarcyidae
- Potamanthidae
- Pseudironidae
- Siphlonuridae
- Heteroptera
- Hymenoptera
- Lepidoptera
- Megaloptera
- Neuroptera (Sisyridae)
- Odonata
- Orthoptera
- Plecoptera
- Trichoptera
- Other Orders
- Keys/Identification
- Aquatic Insects of Michigan
Orders of Aquatic and Semiaquatic Insects
Below is a provisional key for insects that one generally encounters in freshwater aquatic and semiaquatic environments (from Daly 1996). Sometimes during sampling terrestrial organisms are taken, and may not key correctly here. In this case the reader is referred to the work by Borrer et al. 1989.
| 1a | a. Wings or wing pads present, fore wings sometimes hard and shell-like, concealing hind wings |
2 |
| b. Legs present | ||
| 1b | a. Wings or wing pads entirely absent | 27 |
| b. Legs present or absent | ||
| 2a(1a) | Wings fully developed, usually conspicuous and movable (adults) |
3 |
| 2b | Wings developing in fixed wing pads (larvae and pupae) | 15 |
| 3a(2a) | Forewings leathery or hard, at least in the basal half |
4 |
| 3b | Wings entirely membranous | 6 |
| 4a(3a) | Sucking mouthparts united in a jointed beak, mandibles concealed |
Heteroptera (Hemiptera), adults |
| 4b | Chewing mouthparts, mandibles visible | 5 |
| 5a(4b) | Forewings leathery, veins distinct; hind femora enlarged for jumping | Orthoptera, adults |
| 5b | Forewings sclerotized, hard (elytra), veins indistinct; hind legs not modified for jumping, but suited for walking or swimming | Coleoptera, adults |
| 6a(3b) | One pair of wings | 7 |
| 6b | Two pair of wings | 8 |
| 7a(6a) | a. Abdomen ending in 2-3 long filaments |
Ephemeroptera, adults |
| b. Mouthparts inconspicuous | ||
| c. Metathorax without club-shaped structure | ||
| 7b | a. Abdomen without conspicuous filaments | Diptera, adults |
| b. Mouthparts well-developed, forming a proboscis | ||
| c. Metathorax with club-shaped halteres | ||
| 8a(6b) | Wings covered with scales or hairs, obscuring venation | 9 |
| 8b | Wings bare or with only minute hairs, wing venation clearly visible | 10 |
| 9a(8a) | a. Wings with scales | Lepidoptera, adults |
| b. Mouthparts usually fitted with a coiled sucking tube | ||
| 9b | a. Wings with hairs | Trichoptera, adults |
| b. Mouthparts without a coiled sucking tube, rather mandibulate | ||
| 10a(8b) | Antennae short, bristlelike, and inconspicuous | 11 |
| 10b | Antennae of various shapes, conspicuous, not bristlelike | 12 |
| 11a(10a) | a. Abdomen ending in 2-3 long filaments | Ephemeroptera, adults |
| b. Wings about equal in size | ||
| 11b | a. Abdomen without long filaments | Odonata, adults |
| b. Wings about equal in size | ||
| 12a(10b) | a. Tarsi 2- or 3- segmented | Plecoptera, adults |
| b. Abdomen ending with 2 conspicuos cerci (reduced in some adult Nemouridae) | ||
| 12b | a. Tarsi 5-segmented (except 3-segmented in some Hymenoptera) | 13 |
| b. Abdomen without conspicuous appendages | ||
| 13a(12b) | a. Abdomen with narrow constriction at junction with the thorax | Hymenoptera, adults |
| b. Marginal veins in basal half of forewing parallel to leading edge | ||
| c. Wings with fewer than 20 closed cells | ||
| also: Aquatic forms very small, usually < 3 mm in length | ||
| 13b | a. Abdomen broadly joined to thorax | 14 |
| b. Front margin of forewing in basal half with many small veins perpendicular to edge | ||
| c. Wings with more than 20 closed cells | ||
| 14a(13b) | Hindwings folded or pleated lengthwise |
Megaloptera, adults |
| 14b | Hindwings not folded | Neuroptera (Sisyridae), adults |
| 15a(2b) | a. Active insects with legs freely movable | nymphs/larvae, 16 |
| b. Not in cocoons or capsule-like cases | ||
| 15b | a. Usually inactive insects, "mummy-like" with appendages drawn up and free or fused to body | pupae, 20 |
| b. Sometimes in cocoons or sealed in capsule-like cases or puparia | ||
| 16a(15a) | Sucking mouthparts united in a jointed beak with mandibles concealed | Heteroptera (Hemiptera), nymphs |
| 16b | Chewing mouthparts, with mandibles distinct | 17 |
| 17a(16b) | a. Hindlegs suited for jumping, hind femora greatly enlarged | Orthoptera, nymphs |
| b. Abdomen without long cerci | ||
| c. Found in moint places and only temporarily in water | ||
| 17b | a. Hindlegs suited for crawling, hind femora not greatly enlarged, approximately the smae size as front and middle femora | 18 |
| b. Abdomen with or without conspicuous terminal appendages | ||
| c. Usually submerged, truly aquatic | ||
| 18a(17b) | Labium (lower lip) masklike, extendable into a graspable, often scoop-like structure longer than the head | Odonata, nymphs |
| 18b | Labium normal, smaller than head, not large and masklike | 19 |
| 19a(18b) | a. Tarsi with one claw (sometimes foretarsi bifurcated, but eminate from one claw base) | Ephemeroptera, nymphs |
| b. Abdomen terminating with 3 (sometimes only 2) long filaments | ||
| c. Gills and or lamellae located on sides of abdomen, may be platelike, filamentous, or feathery | ||
| 19b | a. Tarsi with two clearly differentiated claws on all legs | Plecoptera, nymphs |
| b. Abdomen terminating only with 2 long filaments | ||
| c. Gills absent or present, fingerlike or filamentous, located at base of mouthparts (inconspicuous), head, coxae, or on thorax or abdomen segments 1-2 (in Michigan) | ||
| 20a(15b) | Appendages free, distinct, not fused to body (exarate) | pupae, 21 |
| 20b | Appendages fused to body (obtect), or concealed in hardened capsule (coarctate) | pupae, 26 |
| 21a(20b) | Abdomen with constriction where joined to thorax | Hymenoptera, pupae |
| 21b | Abdomen broadly joined to thorax | 22 |
| 22a(21b) | One pair of wingpads | Diptera, pupae |
| 22b | Two pair of wingpads | 23 |
| 23a(22b) | a. Pads of forewings thickened | Coleoptera, pupae |
| b. Antennae usually with 11 or fewer segments | ||
| 23b | a. Pads of forewings not thickened | 24 |
| b. Antennae 12 or more segments | ||
| 24a(23b) | a. Mandibles curved, projecting forward and usually crossing each other | Trichoptera, pupae |
| b. Pupae usually submerged in water (maybe in damp areas of overhanging stream banks) | ||
| also: Always in cases | ||
| 24b | a. Mandibles not as above, rather stout and not crossing each other | 25 |
| b. Pupae terrestrial (near water's edge), not normally submerged | ||
| 25a(24b) | a. Smaller, body length < 10 mm | Neuroptera (Sisyridae), pupae |
| b. Pupae in double-walled, meshlike cocoons in sheltered places | ||
| 25b | a. Larger, body length > 12 mm | Megaloptera, pupae |
| b. Pupae in chambers in soil or rotten wood, without cocoons | ||
| 26a(20b) | a. Appendages visible on pupal surface | Lepidoptera, pupae |
| b. Without obvious breating tubes or gills | ||
| c. Two pairs of wingpads present (hindwings mostly concealed beneath forewings) | ||
| 26b | a. Appendages visible or entirely concealed in barrel-shpaed capsule | Diptera, pupae |
| b. If appendages visible, then usually with projecting respiratory organs, or paired, dorsal, prothoracic breating tubes, sometimes with gills at the abdominal tip | ||
| c. One pair of wingpads | ||
| 27a(1b) | a. Abdomen with 6 or fewer segments, with a ventral tube (collaphore) | Collembola, immatures and adults |
| b. Minute, body length < 5 mm | ||
| 27b | a. Abdomen with more than 6 segments, without a ventral tube | 28 |
| b. Body length longer, usually > 5 mm | ||
| 28a(27b) | Three pairs of jointed legs present on thorax | 29 |
| 28b | True legs absent; fleshy, leglike protuberances or prolegs may be present on thorax, but fewer than three pairs and not jointed | 34 |
| 29a(28a) | a. Middle- and hindlegs long and slender, extending considerably beyond the abdomen | Heteroptera (Hemiptera), nymphs and adults |
| b. Compound eyes present (nymph, wingless adult Gerridae) | ||
| 29b | a. Legs not longer than the abdomen | 30 |
| b. Compound eyes absent | ||
| 30a(29b) | Abdomen with at least two pairs of ventral, fleshy, leglike protuberances tipped with tiny hooks (prolegs with crochets) | Lepidoptera, larvae |
| 30b | Abdomen without leglike protuberances, or, if present, not tipped with tiny hooks | 31 |
| 31a(30b) | a. Last abdominal segment with lateral appendages bearing hooks (anal hooks) | Trichoptera, larvae |
| b. Antennae 1-segmented, inconspicuous | ||
| c. Gills, if present, seldom confined to lateral margins of body | ||
| also: Larvae free-living or in cases made of stone or sand grains and/or bits of plant matter | ||
| 31b | a. Last abdominal segment without anal hooks | 32 |
| b.Or, if anal hooks present, antennae of more than 1 segment | ||
| c. Gill insertions lateral | ||
| 32a(31b) | a. Mouthparts formed with mandibles and maxillae united at each side to form long, straight or slightly recurved thread-like suctorial tubes | Neuroptera (Sisyridae), larvae |
| b. Laterally inserted, segmented gills folded beneath abdomen | ||
| c. Body length small, < 10 mm | ||
| d. Found in or on freshwater sponges | ||
| 32b | a. Mounthparts with mandibles not united with maxillae, if mandibles suctorial, then strongly curved | 33 |
| b. Gills seldom segmented and not folded beneath abdomen | ||
| c. Body length variable | ||
| d. Not directly associated with sponges | ||
| 33a(32b) | a. Abdomen with 7 or 8 pairs of lateral filaments or gills, arranged 1 pair on each segment | Megaloptera, larvae |
| b. Ab9 with hooked lateral appendages (anal hooks), or a single, medial, caudal filament | ||
| 33b | a. Abdomen usually without lateral gills, or, if present, then 1) anal hooks absent, or 2) Ab10 with 4 gills, or 3) caudal appendage paired or absent, never single | Coleoptera, larvae |
| 34a(28b) | Head capsule distinct, partly or entirely hardened, and usually pigmented, but may be deeply withdrawn in prothorax | 35 |
| 34b | Head capsule absent, not distinct, hardened, or pigmented, often consisting of a few pale rods | 36 |
| 35a(34a) | Posterior end of body with at least one or a combination of gills, hair brushes, a sucker, or breathing tube | Diptera (in part), larvae |
| 35b | Posterior end of body simple, or with small processes or isolated hairs, but without gills, brushes, suckers, or breathing tubes | Coleoptera (Curculionidae), larvae |
| 36a(34b) | a. Body usually > 5 mm, elongate, somewhat cylindrical, spindle-shaped or maggotlike | Diptera (in part), larvae |
| b. Mouthparts may be reduced to a pair of retractile mouth hooks that move vertically | ||
| 36b | a. Body usually < 5 mm | Hymenoptera, larvae |
| b. Mouthparts may be reduced to a pair of opposable, acute mandibles that move horizontally; parasitoids on or inside insect hosts | ||
References
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Borrer DJ, Triplehorn CA, Johnson NF. 1989. An Introduction to the Study of Insects (6th Edition). Saunders College Publications: Philadelphia, Pennsylvania. 875 p.
Daly HV. 1996. General classification and key to the orders of aquatic and semiaquatic insects, pp. 108-112 in Merritt RW, Cummins KW, An Introduction to the Aquatic Insects of North America, 3rd Edition. Kendall/Hunt Publishing Co.: Dubuque, Iowa. xiii + 862 p.
Page created: May 19, 2003; Last edited: November 05, 2013 (EB)