KEYS TO ORDERS AND GROUPS OF INSECT AND RELATED PESTS

Following are four keys: one for adult pests and three for immature stages. In general, the adult stages are most easily differentiated (especially in winged insects). However, it is not always easy to tell if a pest which is not winged is mature or immature. The following truisms may help to decide which key to use: (1) if a pest has wings, it is an adult insect; (2) if a pest is mating, laying eggs, or giving birth to young, it is in the adult stage. Otherwise, the pest should key out successfully in the immature keys, even if it is an adult.

Immature pests (and wingless adults) may not be easy to distinguish; therefore, in the keys to immature pests, the pests have been broken down by the portion of the plant infested (blossom and leaf, stem, root). Once a pest has been identified to order or group, it may be possible by using the host index at the back of this manual and the insect notes to determine exactly which pest is involved.

Specimens can be submitted for free diagnosis to the county extension office in each county. County agricultural extension agents have been trained in how to properly handle insect and plant specimens for diagnosis. Some counties have formal diagnostic county plant clinics. As a further resource, North Carolina State University houses a Plant Disease and Insect Clinic. Once a pest has been identified, a pesticide or some other control measure may be recommended.

Key to Adults

  1. Wings present (Figs. 2A to F)

    Wingless (Figs. 2G to N)

  2. Front pair of wings (the wings which lie on top when folded) partially or completely thickened and leathery (Figs. 3A to C)

    Front pair of wings flexible and papery, sometimes clear (Figs. 3D to H)

  3. Front pair of wings usually hard, thick, opaque and lacking veins (Fig. 4A) mouthparts chewing type (Fig. 4B to D) - BEETLES

    Front pair of wings usually leathery, with veins (Fig. 4E); mouthparts chewing type or extended into a tube (Fig. 4F)

  4. Mouthparts chewing type (Fig. 4B to D); hind legs modified for jumping (Fig. 4E) or front legs modified for digging (Fig. 3B)

    Mouthparts extended into a tube (Fig. 4F); hind legs usually not modified for jumping - BUGS

  5. Only one pair of wings present, wings usually clear (Fig. 2A); mouthparts adapted for sponging or sucking; second pair of wings represented by small knobs (Fig. 5) - FLIES

    Two pairs of wings present (Fig. 2B,C); mouthparts other than sponging

  6. Mouthparts chewing type (Fig. 4B to D); wings with network of light tiny veins evenly covering surface, front wings similar in size to hind wings; fragile insects; antennae filiform (Fig. 5B)

    Mouthparts extended into tube or hair-like structure, or not chewing type (Fig. 4F, 6A); hind wings usually smaller than front wings; antennae variable

  7. Wings with many cross veins and branches of veins; insect usually solitary; tarsi five-segmented (Fig. 6B) - LACEWINGS AND RELATIVES

    Wings with reduced venation, but having vein-like wrinkles (Fig. 6C); insect usually in colony; tarsi four-segmented - TERMITES

  8. Wings covered with tiny scales which resemble dust when smudged on one's finger (Fig. 7); mouthparts long, thread-like (Fig. 6A) - BUTTERFLIES

    Wings without scales; mouthparts variable or lacking

  9. Body with honey tubes or "exhaust pipes" (cornicles); slow-moving insects; seem to reproduce rapidly (Fig. 8) - APHIDS

    Body without honey tubes

  10. No legs; soft, slimy, sometimes with a helical shell (Figs. 9A,B) - SLUGS, SNAILS

    Legs present

  11. More than or less than six legs present (Fig. 2H,M,N)

    Six legs usually present; legs and antennae well developed; body with honey tubes; mobile (Fig. 2L) - APHIDS

  12. Four pairs of legs present; usually associated with chlorotic stippling of host plant leaves; tiny sink "spider webs" on heavily infested plant; chlorotic stippling symptoms developing rapidly; legs arranged somewhat like a typical spider; color variable (Fig. 10) - SPIDER MITES

    More than four pairs of legs present

  13. Seven pairs of legs present; oval; sometimes capable of rolling up into a ball (Fig. 2K) - SOWBUGS, PILLBUGS

    Many pairs of legs present; sides straight; long, slender, sometimes coiling into a helix (Fig. 2N) - MILLIPEDES

  14. Small insects (2 mm or less); run or flutter when disturbed

    Slightly larger insects (2 to 10 mm); jump when disturbed (Fig. 11) - LEAFHOPPERS

  15. White insects (up to 2 mm) which resemble tiny moths; often found on the undersides of host plant leaves; often associated with honeydew and sooty molds; flutter when disturbed (Fig. 3H, 12A) - WHITEFLIES

    Orange, brown or black insects (up to 2 mm) which are slender and spindle-shaped; often found in buds or flowers, foliage, and even corms; often associated with chlorosis and distorted growth; run or fly when disturbed (Figs. 2B, 12B) - THRIPS

KEYS TO IMMATURE STAGES

Blossom, Leaf and Fruit Feeders

  1. Chewing mouthparts (leaf removed or consumed by pest (Fig. 4B to D)

    Mouthparts extended into a tube or hair-like structure (Fig. 4F), leaf may be distorted or discolored but not consumed by pest

  2. Insect inside leaf, fruit, pod, etc.

    Pest on exterior of plant

  3. Insect mining in foliage

    Insect feeding inside fruit, pod, etc.

  4. Legless insect making mines in leaves - LEAFMINING MAGGOTS

    Insect mining in leaves and later hiding in rolled up leaves; has three pairs of legs and five pairs of prolegs (Fig. 13A)

  5. Larva legless

    Larva with legs

  6. Fairly hard-bodied larva; yellow or white; slender and roughly cylindrical with pointed head and rounded abdomen (Fig. 13B) - MAGGOTS

    Fairly soft-bodied larva; color variable, usually white, grayish white, or pale yellow with dark h head; body somewhat curved or C-shaped (Fig. 13C)

  7. Larva with three pairs of legs near the head and five, four, or three pairs of prolegs (Fig. 14A to C) - MOTH CATERPILLARS

    Larva with three pairs of legs near the head and one pair of anal prolegs (Fig. 15A to C) - BEETLE LARVAE

  8. Legless larva

    Larva with legs

  9. Slime trail often noticed on damaged portion of plant; dark-colored, soft-bodied, slimy animal, sometimes with a helical shell (Fig. 16A, B) - SLUGS AND SNAILS

    Fairly soft-bodied larva; color variable, usually pale green with dark head; body somewhat curved or C-shaped (Fig. 13C) - WEEVIL LARVAE

  10. Larva with three pairs of legs near the head and at least three pairs of fleshy prolegs on the abdomen (Fig. 14A to C) - MOTH OR BUTTERFLY CATERPILLARS

    Larva with three pairs of legs near the head; either one pair of prolegs at the tip of the abdomen or no prolegs (Fig. 15A to C) - BEETLE LARVAE

  11. Pest mobile, with honey tubes (cornicles) on the abdomen and a tail-like cauda (Fig. 17A,B) - APHIDS

    Mobility variable; no cornicles or cauda on abdomen

  12. Almost microscopic; three or four pairs of legs; usually associated with very fine webbing, spherical eggs, chlorotic stippling of host plant, and adult spider mites (Fig. 18) - SPIDER MITES

    Not as above

  13. Very small, active, orange to yellow, spindle-shaped insect; feeds in buds and flowers, or on leaves (Fig. 19A to D) - THRIPS

    Not as above

  14. Immobile (except newly hatched "crawler" stage); body adhering to plant surface so legs are not visible; slightly flattened body; associated with tiny white mouth-like insects (Fig. 20A to E) - WHITEFLY NYMPHS

    Mobile legs visible

  15. Jumps when disturbed; elongate body (Fig. 21A) - LEAFHOPPERS

    Runs when disturbed; body oval in top view (Fig. 21B) - PLANT BUGS

Stem Borers

  1. Head very dark (appears black); body slender, white and legless (Fig. 22) - FUNGUS GNAT LARVAE

    Not as above; legs usually present

  2. Cylindrical body with three pairs of legs near the head and five pairs of prolegs (Fig. 23) - MOTH CATERPILLARS

    Body flattened somewhat; usually three pairs of tiny legs near the head (in some cases, legs not present (Fig. 24) - BEETLE LARVAE

Root- or Tuber-Feeding Pests

  1. Legless

    Three or more pairs of legs

  2. Body soft, slimy, dark gray or black with a ridge down the back and a diamond shape near the center; tunnels through soil (Fig. 25) - GREENHOUSE SLUG

    Not as above

  3. Dark head contrasting with lightly covered body

    Head not easily distinguishable from the rest of the body

  4. Fairly hard-bodied; yellow or white; slender and roughly cylindrical with pointed head and rounded abdomen (Fig. 26A) - MAGGOTS

    Fairly soft-bodied, grub-like insect; usually in or near damaged bulbs or corms (Fig. 26B) - BULB FLY LARVAE

  5. Head very dark (almost black); body slender and white (Fig. 27A) - FUNGUS GNAT LARVAE

    Head brown to black; body plump and usually curved or C-shaped (Fig. 27B) - WEEVIL LARVAE

  6. Two pairs of legs on most segments; worm-like; hard-bodied, with three to many pairs of legs; curls up when disturbed (Fig. 27C) - MILLIPEDES

    Not as above

  7. Three pairs of legs near the head and at least one pair of short, stumpy prolegs near the tip of the abdomen

    Three pairs of legs and no short, stumpy prolegs on abdomen

  8. Three pairs of legs near the head and five pairs of prolegs on the abdomen (Fig.28A) - MOTH CATERPILLARS

    Three pairs of legs near the head and one pair of prolegs near the tip of the abdomen (Fig. 28B) - BEETLE LARVAE

  9. Front legs shovel-like for digging; dark brown insect covered with fine short hairs (Fig. 29A) - MOLE CRICKET NYMPHS

    Front legs not shovel-like

  10. White or dirty white grubs with dark head; wide variation in size; body slightly C-shaped and darker in color (Fig. 29B) - BEETLE LARVAE

    Small jumping insect (1 to 3 mm long) with relatively short legs; sometimes with blunt antennae (Fig. 29C) - SPRINGTAILS

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