1. Slender and elongate with long slender legs (Ranatra) or elongate-oval (Nepa apiculata Uhler).
2. Front legs raptorial
3. Terminal abdominal appendage long, slender, froming a nonretractable breathing tube.
1. Brownish, oval, flattened, ca. 1-2 in.
2. Front legs raptorial
3. Terminal abdominal appendage short, retractile.
4. Lethocerus, Belostoma
1. Elongate, oval, with the dorsal surface of the body flattened, usually dark gray in color.
2. Dorsal surface of the hemelytra with dark narrow crosslines
3. Front legs short, tarsi 1-segmented and scoop-shaped
4. Hind legs elongate, functioning as oars
1. Small toad-shaped bugs.
2. Ocelli present
3. Front legs shorter than middle legs
4. Gelastocoris
1. Dark brown to black, oval
2. Membrane in forwing without veins
3. Front femora greatly thickened
1. Resemble corixids but with dorsal surface of body convex and often light colored.
2. Dorsal surface of the hemelytra without dark narrow crosslines
3. Front tarsi not scoop-shaped
4. Swim upside down.
1. Grayish, the body and legs very slender, ca. 8 mm. Resemble tiny walking sticks.
2. Usually wingless
3. Head long and slender, eyes bulging located slightly behind the middle of the head.
4. Hydrometra
1. 3 mm or less
2. Broad-shouldered appearance.
3. Body covered with pubescence.
1. Usually less than 5 mm.
2. Middle legs arise about equidistant between front and hind legs (broad shouldered appearance).
3. Usually wingless
4. Brown or black, often with silvery markings.
1. Usually less than largers than 5 mm. Body long and narrow.
2. Middle legs arise closer to hind legs than to front legs.
3. Front legs short and the other are long and slender.
4. Winged and wingless adults in many species.
5. Dark-colored.
1. Small, oval, flattened.
2. Membrane of fore wings with 4-5 closed cells.
3. Antennae 4-segmented
4. Beak and tarsi 3-segmented.
5. Ocellia close together.
1. Body and wings with reticulate sculpturing. Usually less than 5.mm.
2. Pronotum with a triangular posterior extension over scutellum.
3. Ocelli absent
4. Beak 4-segmented
5. Tarsi 1-2-segmented
1. Small oval or elongate, usually less than 10 mm.
2. Forewing with cuneus and membrane with 1-2 closed cells.
3. Ocelli absent
4. Beak 4-segmented
5. Tarsi 3-segmented
1. Elongate, oval, relatively slender, 3.5-11 mm in length
2. Forewing, when developed, with a number of small cells around margin.
3. Ocelli present
4. Front femora slightly thickened
5. Beak generally 4 segmented
1. Flat, oval, usually reddish brown, 6 mm or less in length.
2. Wingless
3. Ocelli absent
4. Antennae 4-segmented
5. Beak and tarsi 3-segmented
1. Head elongate with the part behind the eyes necklike.
2. Beak short, 3-segmented fitting into a stridulatory groove in the prosternum
3. Ocelli present, except in Emesinae.
4. Antennae 4-segmented
5. Edges of abdomen often extending beyond wings.
6. Wheel bug, Arilus cristatus (L.)
1. Small, oval, dark, very flat.
2. Wings narrow, abdomen extends beyond wings.
3. Ocelli absent.
4. Antennae and beak 4-segmented
5. Tarsi 2-segmented
1. Slender, usually brownish, 5-9 mm.
2. Antennae long and slender, 4-segmented
3. Front legs not raptorial.
4. Ocelli present.
5. Beak 4-segmented
6. Tarsi 3-segmented
1. Elongate to oval, Small to medium sized 2-18 mm.
2. Membrane of forewing with only 4 or 5 veins.
3. Cuneus lacking
4. Ocelli usually present.
5. Antennae and beak 4-segmented
6. Front femora sometimes thickened (appear raptorial).
1. Similar to Lygaeidae but without ocelli
2. Ocelli absent.
3. Membrane of forewing with many veins.
4. Front femora never thickened.
1. Similar to Lygaeidae but with many veins in forewing
2. Ocelli present.
3. Hind tibiae sometimes dilated and leaflike.
1. Broadly oval and shield-shaped, 8-10 mm.
2. Scutellum very large, broadly oval, and extending to apex of abdomen.
3. Pronotum without a prominent tooth on each side.
4. Antennae 5-segmented.
1. Broadly oval and shield-shaped, 8-10 mm.
2. Scutellum large and triangular and not reaching to apex of abdomen.
3. Pronotum with a prominent tooth on each side.
4. Antennae 5-segmented.