Placed on the Web by the Center for IPM, NC State University

Keys to Insect and Other Pests of Man and Animals

Keys are devices to help the reader decide what kind of insect, mite, or rodent is causing a problem. These keys are a series of couplets which force the reader to make a series of choices. Although keys are not easy to use, they do alert the reader to the kinds of characteristics used to distinguish different kinds of pests. Close examination with a 10 power hand lens or a stereomicroscope is often necessary to identify insect and mite pests. However, microscopic pests (invisible to the unaided eye) are not included in these keys.

All life stages for each pest are not included in these keys, but at least the adult stage for each pest is given and the damaging stage of each pest is given. Some minor common pests which are not covered later in the insect notes are included in the key because of the possibility of the reader encountering such a pest.

The language used in keys is telegraphic to conserve space. The lack of verbs and articles may be confusing at first, but with a little practice perhaps it will not seem too strange. When writing about the wings of flies in this key, the orientation of the wing is presumed to be straight out sideways from the body. Even though the wings of a specimen may be folded back over its abdomen, the user of the key must try mentally to orient the wing so the terms front margin and rear margin are meaningful. Whenever technical terms such as "oral vibrissae" or "costa vein" are used, these structures are illustrated close by.

Key to Rodents

  1. Adult 13 to 20 cm long from head to tip of tail (Fig. 1A); droppings (excrements) pointed and up to 6 mm long (Fig. 1B); nests in furniture, walls of houses, feed sacks, etc. . . HOUSE MOUSE

    Adult 32 to 46 cm long from head to tip of tail (Fig. 1C); droppings capsule-shaped and 13 to 20 mm long (Fig. 1D); particularly common in association with man along stream banks, canals, and other bodies of water. . . NORWAY RAT

Key to Insects and Mites

  1. Having 6 or 8 legs (Fig. 2). . . go to 2

    Legless and worm-like maggots (Fig. 3). . . . go to 34

  2. Having 6 legs and a distinct head (Fig. 2A) . . . go to 3

    Having 8 legs without a distinct head (Fig. 2B) . . . go to 32

  3. One pair of wings (Fig. 4A) . . . go to 4

    Two pairs of wings or no wings (Fig. 4B, C) . . . go to 21

  4. Antennae (feelers) with 10 or more distinct segments (Fig. 5A) . . . go to 5

    Antennae with 3 segments (Fig. 5B) or the apical segments more or less fused (Fig. 5C) . . . go to 7

  5. Short antennae with 10 or 11 segments (Fig. 6A); wing veins slender at rear (Fig. 6B); slightly humpbacked fly 4 mm long or less; bite usually painless at first but later causes swelling and pain . . . BLACK FLY or BUFFALO GNAT

    Longer antennae with 12 to 16 segments (Fig. 6C); wing veins all about the same width (Fig. 6D) . . . go to 6

  6. Wings not very hairy, costa vein ending before wing tip (Fig. 7A); blood-sucking fly (Fig. 7B) 0.5 to 5.0 mm long . . . BITING MIDGE, PUNKIE, NO-SEE-UM

    Wings scaly and with numerous veins, costa vein continuing around wing tip (Fig. 7C); slender, long-legged fly (Fig. 7D) with wings 3 to 4 mm long; has slender proboscis for sucking blood . . . MOSQUITO

  7. Each wing with 4 or 5 cells along rear edge (Fig. 8A) . . . go to 8

    Each wing with 3 or fewer cells along rear edge (Fig. 8B) . . . go to 9

  8. Third wing vein branched with vein 3A long and vein 3B ending behind wing tip (Fig. 9A); abdomen flattened; small- to large-bodied fly (Fig. 9B) 10 to 19 mm long; female inflicts painful bite . . . HORSE or DEER FLY

    Third wing vein branched with vein A short and vein B ending before wing tip (Fig. 9C); dusky-winged, nonbiting fly (Fig. 9D) 15 to 20 mm long; wasp-like in appearance; bronze or primarily black abdomen . . . BLACK SOLDIER FLY

  9. Second antennal segment with seam (Fig. 10A); mesonotal suture on thorax goes all the way across (Fig. 10B) . . . go to 10

    Second antennal segment without seam (Fig. 10C); mesonotal suture absent or not reaching all the way across (Fig. 10D) . . . go to 11

  10. Hypopleura (area just above base of hind legs) bare or with sparse, fine hairs (Fig. 11A) . . . go to 13

    Hypopleura with row of strong bristles or with long, dense hairs (Fig. 11B) . . . go to 19

  11. Oral vibrissae (hairs near the front of the mouth) usually present (Fig. 12A); nonbiting, gray to black fly only about 1.2 mm long; passes easily through 16-mesh screen . . . EYE GNAT

    Oral vibrissae usually absent (Fig. 12B); fly 15 to 18 mm long . . . go to 12

  12. Spurious (extra) vein present (Fig. 13A) and anal cell nearly reaches wing margin (Fig. 13B); hairy, brownish to black, bee-like fly about 15 mm long; has mouthparts but does not bite . . . DRONE FLY

    Anal cell short (Fig. 13C); hairy, brownish to reddish fly about 18 mm long; mouthparts absent . . . BOT FLY

  13. Slender, shiny black, nonbiting fly (Fig. 14) about 5 mm long . . . GARBAGE or DUMP FLY

    Fly dull, not shiny . . . go to 14

  14. Fly usually less than 6 mm long . . . go to 15

    Fly usually longer than 6 mm . . . go to 16

  15. Brownish-gray to black with yellowish cast to body; blood-sucking; 3.5 to 4 mm long; set of parallel stripes just behind head (Fig. 15A); brownish-red antennae; usually a pest of cattle and horses . . . HORN FLY

    Slender, nonbiting fly 5 to 6 mm long; dark-colored body with or without stripes (Fig. 15B); hovering and jerky pattern of flight . . . LITTLE HOUSE FLY

  16. Blood-sucking fly with sharp mouthparts which protrude from head (Fig. 16A); body 6 to 8 mm long; 4 dark, longitudinal stripes on thorax; several dark spots on abdomen; "squats" when at rest . . . STABLE FLY

    Mouthparts blunt, not protruding (Fig. 16B); nonbiting fly . . . go to 17

  17. Pale spot on top of thorax near abdomen; 4 dark, sometimes indistinct, stripes on thorax; abdomen black or black and red; body about 8 mm long (Fig. 16B) . . . FALSE STABLE FLY

    Not as above . . . go to 18

  18. Abdomen yellow or partially yellow with dark line down the middle; gray fly (Fig. 17A) about 6.5 mm long with 4 dark, lengthwise stripes on thorax . . . HOUSE FLY

    Abdomen primarily black with orange base (female) or orange-brown with black base and dorsal stripe (male); thorax gray with 4 dark, length-wise stripes (Fig. 17B); body 6 to 8 mm long; commonly feeds on moist animal secretions . . . FACE FLY

  19. Hypopleura (area above base of hind legs) obscured by long, usually dense hairs; mouthparts absent; body about 13 mm long with 2 bands of yellow and white hairs across it (Fig. 18A); reddish-orange hairs at tip of abdomen and on legs; wings dark brown to black . . . CATTLE GRUB FLY

    Hypopleura with a row of strong bristles (Fig. 18B) . . . go to 20

  20. Notopleura ("shoulder" of the thorax) usually with 4 bristles (Fig. 19A); gray fly about 10 to 13 mm long; 3 black stripes on thorax; light and dark checkerboard pattern on abdomen (Fig. 19B) . . . FLESH FLY

    Notopleura with only 2 bristles (Fig. 19C); black or metallic-colored fly 6 to 14 mm long; no stripes or checkerboard pattern (Fig. 19D) . . . BLOW FLY

  21. Two pairs of wings; constricted "waist" without nodes (bumps); smooth-bodied, stinging insect (Fig. 20A) 13 to 25 mm long; color variable; associated with papery nests under or above ground . . . HORNET, WASP, YELLOW JACKET

    No wings; "waist" constricted with nodes (Fig. 20B) or not constricted (Fig. 20C) . . . go to 22

  22. Constricted "waist" with nodes (Fig. 20B); body usually reddish or dark brown and 3 to 6 mm long; stinging ant associated with mounds 35 cm or more in diameter and 20 to 25 cm high . . . FIRE ANT

    No constricted "waist" as above . . . go to 23

  23. Body flattened laterally (from side to side); spiny, hard-skinned insect (Fig. 20C) 1 to 2.5 mm long; hind legs modified for jumping . . . FLEA PESTS OF MAN and FLEA PESTS OF ANIMALS

    Body not flattened laterally . . . go to 24

  24. Pest 1 mm or less in length; associated with slightly larger, 8-legged animals which are otherwise similar in appearance (Fig. 21A, B) (key out the larger, 8-legged pests) . . . go to 31

    No association as above; all animals with 6 legs; size variable; body somewhat flattened dorsoventrally (from top to bottom) (Fig. 21C) . . . go to 25

  25. Chewing mouthparts; yellowish-white louse with broad, flat, reddish head (Fig. 22A); body up to 1.5 mm long with 8 dark crossbands on abdomen . . . go to 26

    Piercing-sucking mouthparts; body somewhat flattened dorsoventrally (from top to bottom) (Fig. 22B) . . . go to 27

  26. Feeding on cattle . . . CATTLE BITING LOUSE

    Feeding on skin or feathers of poultry . . . CHICKEN BODY LOUSE

  27. Jointed beak (Fig. 23A); reddish-brown, oval, flattened insect up to 9 mm long; small, pad-like wing remnants (Fig. 23B); pronotum (just behind head) collar-like . . . BED BUG

    Beak not jointed, sometimes retracted into head . . . go to 28

  28. Needle-like mouthparts exposed (Fig. 24A); short, thick legs with apical spurs; body about 6 mm long; blood-sucking parasite of sheep . . . SHEEP KED

    Mouthparts retracted into head; blood-sucking louse (Fig. 24B) . . . go to 29

  29. Parasite of hogs; oval, grayish-brown louse up to 6 mm long; brown and black markings on body; legs claw-like (Fig. 25A) . . . HOG LOUSE

    Parasite of man; grayish-white louse 4 mm or less in length. go to 30

  30. Abdomen longer than wide; body up to 4 mm long without hairy tubercles (Fig. 25B); all legs about equal in size . . . HEAD AND BODY LOUSE

    Abdomen about as long as wide; body up to 2 mm long with hairy tubercles (Fig. 25C); front pair of legs more slender than other pairs . . . CRAB LOUSE

    go to 32

    No constricted "waist" (Fig. 27); blood-sucking parasite of man and animals; some immature stages 6 legged . . . go to 33

  31. Spider with black, globular abdomen about 9 by 13 mm with red or yellow, hourglass marking on underside (Fig. 26A, B) . . . BLACK WIDOW SPIDER

    Grayish- to reddish-brown spider with black, fiddle-like marking on the head and thorax; body 7 to 13 mm long with a leg span about the size of a half dollar (Fig. 26C) . . . BROWN RECLUSE SPIDER

  32. Hairless body from 0.5 mm up to 7 mm long (immature to adult) (Fig. 27A; usually brown, reddish-brown, or gray . . . Tick

    Body with long or short hairs (Fig. 27B, C); body usually 1.25 mm long or less; color variable . . . CHIGGER, EAR MITE, ITCH MITE or POULTRY MITE

  33. With a definite head (Fig. 28A) . . . go to 35

    Without a definite head (the mouthparts are tucked into the thorax (Fig. 28B) . . . go to 36

  34. Body large and flattened, 12 to 27 mm long when fully grown; creamy white to reddish-brown; develops in decaying organic matter (Fig. 28A) . . . BLACK SOLDIER FLY LARVA

    Slender, aquatic larva up to 10 mm long or curled pupa; transparent to greenish-brown; develops in still rather than running water (Fig. 29A, B) . . . MOSQUITO LARVA and/or PUPA

  35. Body with pointed projections on each segment (Fig. 30A); posterior spiracles (breathing openings) on small bumps; white to light brown body up to 8 mm long . . . LESSER HOUSE FLY LARVA

    Body smooth or with short spines; no long pointed projections; posterior spiracles not on bumps (Fig. 30B) . . . go to 37

  36. Leathery; aquatic; larva up to 20 mm long, with long, tail-like breathing tube (Fig. 31A) . . . RAT-TAILED MAGGOT

    Larva without a tail-like process (Fig. 31B) . . . go to 38

  37. Hard, dark line (peritreme) present around hind spiracles; each spiracle with 3 distinct slits (Fig. 32A) . . . go to 39

    No peritreme around hind spiracles (Fig. 32B); or, if peritreme present, then 3 slits absent (Fig. 32C) . . . go to 45

  38. Slits of hind spiracles straight (Fig. 33A) . . . go to 40

    Slits of hind spiracles strongly curved (Fig. 33B) . . . go to 44

  39. Peritreme of hind spiracle very thin on top and bottom (Fig. 34A); spiracles slightly elevated and, when viewed from rear, slanted toward each other; hardened, spiny larva at least 10 mm long when fully grown; develops in decaying organic matter . . . BLACK GARBAGE or DUMP FLY LARVA

    Peritreme complete (Fig. 34B) or with only lower portion missing (Fig. 34C) . . . go to 41

  40. Hind spiracles and peritreme complete (Fig. 35A); at least one of the two prothoracic spiracles (close to front end) with 8 or more openings (Fig. 35B, a green bottle fly) or prothoracic spiracles with 6 or less openings (Fig. 35C, a bronze bottle fly); yellowish to white maggot up to 14 mm long; develops in decaying organic matter, sometimes carrion or animal wounds . . . BOTTLE FLY LARVA

    Hind spiracles with peritreme incomplete, not enclosing a "button" (the "button" is a tiny, round pale area which is sometimes hard to see, Fig. 35D) . . . go to 42

  41. Slits of hind spiracle not pointing toward opening in peritreme (Fig. 36A); white to yellowish maggot 10 to 22 mm long when fully grown; develops in wounds, carrion or excrement . . . FLESH FLY LARVA

    Slits of hind spiracle pointing toward opening in peritreme (Fig. 36B); at least one of the two prothoracic spiracles (close to front end) with 10 or more openings (Fig. 36C) . . . go to 43

  42. Hind spiracle with button distinct or absent, walls of slits with lateral swellings (Fig. 37A); white or yellowish maggot up to 18 mm long; develops only on dead animal tissues . . . SECONDARY SCREWWORM

    Hind spiracle with button present, walls of slits without lateral swellings (Fig. 37B); white or yellowish maggot up to 17 mm long; develops in decaying organic matter, carrion, or animal wounds . . . BLACK BLOW FLY LARVA

  43. Peritreme of hind spiracle thick (Fig. 38A); nearly white maggot up to 13 mm long; common in moist feces and decaying organic matter . . . HOUSE FLY LARVA

    Peritreme of hind spiracle thin (Fig. 38B); white maggot 6.5 to 7.5 mm long when fully grown; common in fresh bovine feces . . . HORN FLY LARVA

  44. Small or slender, maggot-type larva usually, but not always, less than 13 mm long, tapering toward the head (Fig. 39A); develops in decaying organic matter . . . go to 46

    Large, robust larva with very stout spines (Fig. 39B); over 15 mm long when fully grown; internal parasite of animals . . . go to 48

  45. Button of hind spiracle centrally located (Fig. 40A); creamy white to pale yellow maggot up to 12 mm long; develops in moist, decomposing organic matter (usually not in manure piles) . . . STABLE FLY LARVA

    Button of hind spiracle not centrally located (Fig. 40B) . . . go to 47

  46. Slits of hind spiracles strongly curved (Fig. 41A); yellowish maggot up to 13 mm long; develops in fresh bovine manure . . . FACE FLY LARVA

    Slits of hind spiracles not strongly curved (Fig. 41B); grayish to cream-colored larva 12 to 18 mm long when fully grown; develops in decaying organic matter, including manure . . . FALSE STABLE FLY LARVA

  47. Hind spiracles with 3 distinct, slightly curved slits (Fig. 42A); yellowish- to dirty-white larva 17 to 24 mm long when fully grown; spines dark brown; internal parasite of horses . . . HORSE BOT FLY LARVA

    Hind spiracles without 3 distinct slits . . . go to 49

  48. Button of hind spiracle not centrally located or enclosed; opening toward button wide (Fig. 42B); white when young; mature larva black, up to 28 mm long and 13 mm wide; subcutaneous along back line of cattle . . . COMMON CATTLE GRUB

    Button of hind spiracle enclosed, centrally located (Fig. 42C); larva more than 15 mm long when mature; body with stout spines . . . SHEEP BOT FLY