Both parts of this couplet lead to the order Odonata, and this couplet separates the two suborders Anisoptera (Dragonflies) and Zygoptera (Damselflies). It's arranged this way because "suborder" is not a taxonomic level included in this site's programming, but it's an important everyday classification in this one case.
Option 1 | Option 2 |
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Wings held together above abdomen or only partly spread when insect is perched | Wings held horizontally when insect is perched |
Eyes separated by more than the width of one eye | Eyes meeting middorsally or separated by a space less than the width of one eye |
Fore and hind wings similar in size and shape, each with a quadrangle instead of a triangle and subtriangle | Fore and hind wings dissimilar in size and shape, with hind wing considerably wider at base than forewing; each with a triangle and subtriangle |
Males with 2 paraprocts | Males with an epiproct which is either entire or bifid |
Females with a fully-developed ovipositor, bearing styli | Females with or without an ovipositor |
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1 Example Specimen | 1 Example Specimen
This specimen of Libella saturata, the flame skimmer dragonfly, is the only invertebrate in this site's collection that I caught by hook and line. It swooped down and attacked my dry fly on the Firehole River, where it lived as a nymph in the hot water near the geothermal springs and geyser runoff.
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Odonata-Zygoptera | Odonata-Anisoptera |
The current couplet is highlighted with darker colors and a icon, and couplets leading to this point have a icon.
Leads to Couplet 2:
- Forewings leathery (semiopaque) or hard, at least in the basal half
Couplet 2
Leads to Couplet 4:
- Wings entirely membraneous, usually transparent between veins, but may be variously colored, darkened, or covered with hairs or scales
Couplet 4
Leads to Couplet 3:
- Mouthparts made for chewing, with mandibles visible
Couplet 3
Leads to Hemiptera:
- Mouthparts made for sucking, with mandible concealed and a jointed beak (rostrum) visible
Leads to Orthoptera:
- Forewings leathery, with distinct veins
- Femora of hind legs greatly enlarged, suited for jumping
Leads to Coleoptera:
- Forewings hard (called elytra), with veins indistinct; hindwings membraneous but often concealed
- Hind legs suited for walking or swimming
Leads to Couplet 6:
- Two pairs of wings, although hindwings may be small or concealed beneath forewings when wings are folded
Couplet 6
Leads to Ephemeroptera:
- Two or three tails
- Mouthparts inconspicuous
- Thorax without halteres
Leads to Diptera:
- No tails (conspicuous filaments at the end of the abdomen)
- Mouthparts well developed, forming a long or short proboscis
- Thorax with halteres
Leads to Couplet 7:
- Wings covered with scales or hairs, obscuring venation
Couplet 7
Leads to Couplet 8:
- Wings bare or with minute hairs; venation clearly visible
Couplet 8
Leads to Lepidoptera:
- Wings covered with scales (broadly flattened hairs)
- Mouthparts usually fitted with a coiled sucking tube (proboscis)
Leads to Trichoptera:
- Wings covered with hairs
- Mouthparts without a coiled sucking tube
Leads to Couplet 9:
- Antennae bristle-like and inconspicuous, usually shorter than head
Couplet 9
Leads to Couplet 10:
- Antennae of various shapes, conspicuous, and not bristle-like, and usually much longer than head
Couplet 10
Leads to Ephemeroptera:
- 2 or 3 tails
- Hind wings much smaller than forewings
Leads to Couplet 13:
- No tails
- Wings about equal in size
Couplet 13
Leads to Plecoptera:
- Tarsi 2- or 3-segmented
- 2 conspicuous tails (except reduced in some Nemouridae)
Leads to Couplet 11:
- Tarsi 5-segmented (except a few Hymenoptera have 3 or 4 segments)
- No tails
Couplet 11
Leads to Couplet 12:
- 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
Couplet 12
Leads to Hymenoptera:
- 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
Leads to Megaloptera:
- Hind wings pleated lengthwise, folded fan-like when closed
- Veins along back edge of wings usually with Y-shaped branches
Leads to Neuroptera:
- Hind wings not pleated, similar to forewings when closed
- Veins along back edge of wings forming many Y-shaped branches
Neuroptera
Leads to Odonata-Zygoptera:
- Wings held together above abdomen or only partly spread when insect is perched
- Eyes separated by more than the width of one eye
- Fore and hind wings similar in size and shape, each with a quadrangle instead of a triangle and subtriangle
- Males with 2 paraprocts
- Females with a fully-developed ovipositor, bearing styli
Leads to Odonata-Anisoptera:
- Wings held horizontally when insect is perched
- Eyes meeting middorsally or separated by a space less than the width of one eye
- Fore and hind wings dissimilar in size and shape, with hind wing considerably wider at base than forewing; each with a triangle and subtriangle
- Males with an epiproct which is either entire or bifid
- Females with or without an ovipositor