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 that 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 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.

KEY TO ADULTS

1. Wings present (Fig. 59A to F) - 2

   Wingless (Fig. 59G to N) -10

2. Front pair of wings (the wings that lie on top when folded) partially or completely thickened and leathery (Fig. 60A to C) - 3

   Front pair of wings flexible and papery, sometimes clear (Fig. 60D to H) - 5

3. Front pair of wings usually hard, thick, opaque, and lacking veins (Fig. 61A); chewing type (Fig.61B to D). - BEETLES

   Front pair of wings usually leathery, with veins (Fig.61E); mouthparts chewing type or extended into a tube (Fig. 61F) - 4

4. Mouthparts chewing type (Fig. 61B to D); hind legs modified for jumping (Fig. 61E) or front legs modified for digging (Fig. 60B) - GRASSHOPPERS, CRICKETS

   Mouthparts extended into a tube (Fig. 61F); hind legs usually not modified for jumping - BUGS

5. Only one pair of wings present, wings usually clear (Fig. 59A) - 8

   Two pairs of wings present (Fig. 59B,C) - 6

6. Mouthparts chewing type (Fig. 61B to D); wings with network of light, tiny veins evenly covering surface, front wings similar in size to hind wings; fragile insects; antennae filiform (Figs. 60G, 62B) - TERMITES

   Mouthparts extended into tube or hairlike structure, modified for sponging or missing altogether (Fig. 62A); wings variable; antennae variable - 7

7. Wings covered with tiny scales that resemble dust when smudged on one's finger (Fig. 63); mouth parts long, threadlike - BUTTERFLIES, MOTHS

   Wings without scales; mouthparts variable or lacking - 9

8. Mouthparts adapted for sponging or sucking; second pair of wings represented by small knobs; no tail filaments (Figs. 59A, 64A) - MIDGES, FLIES

   Mouthparts absent; second pair of wings sometimes represented by small knobs (sometimes absent); usually with terminal waxy filaments (Fig. 64B) - MALE MEALYBUGS AND SCALES

9. Body with "honey tubes" or "exhaust pipes;" slow-moving insects; seem to reproduce rapidly (Fig. 65) - APHIDS

   Body without "honey tubes" - 20

10. No legs; soft, slimy, sometimes with a helical shell (Fig. 66A,B) - SLUGS, SNAILS

    Legs present - 11

11. More than or fewer than six legs present (Figs. 59H,M,N; 67) - 12

    Six legs usually present (legs may be reduced and obscure in many scale insects) (Fig. 59 I,J,L) - 17

12. Microscopic, often associated with galling or distorted plant growth - 13

    Visible to the unaided eye (with 20-20 vision); damage not usually characterized by galls and distorted growth -14

13. Two pairs of legs present; wormlike, usually associated with galls, erineums or chlorosis of host plant (Fig. 67) . - ERINEUM, GALL, OR RUST MITES

    Four pairs of legs present; oval; females with hind legs threadlike; usually associated with distorted growth (Fig. 68). - THREAD-LEGGED MITES

14. Four pairs of legs present; usually associated with chlorotic stippling of host plant leaves (Fig.59H) -15

    More than four pairs of legs present - 16

15. Tiny silk "spider webs" on heavily infested plant; chlorotic stippling symptoms developing rapidly; legs arranged somewhat like those of a typical spider; color variable (Fig. 59H) - SPIDER MITES

    No silk webbing on heavily infested plants; chlorotic stippling symptoms developing slowly; legs more or less pointing forward and backward; color red (Fig. 69) - FALSE SPIDER MITES

16. Seven pairs of legs present; oval; sometimes capable of rolling up into a ball (Fig. 59K) - SOWBUGS, PILLBUGS

    Many pairs of legs present; sides straight, long, slender, sometimes coiling into a helix (Fig. 59N) - MILLIPEDES

17. Body covered by shell-like secretion, which can often be pried loose without dislodging insect (Fig. 70) - ARMORED SCALES

    No secretion on body, or if secretion is present, then it cannot be pried loose without dislodging insect - 18

18. Body usually naked - 19

    Usually covered with a white, waxy bloom that resembles flour or white, waxy threads (Fig. 59J) - MEALYBUGS, WOOLLY APHIDS, ADELGIDS, (and less often) SOFT SCALES

19. Legs and antennae well developed; body with "honey tubes" or "exhaust pipes;" mobile (Fig. 59L) - APHIDS

    Legs and antennae obscure; no "honey tubes;" often immobile. - SOFT SCALES

20. Small insects (2 mm or less); run or flutter when disturbed - 21

    Slightly larger insects (2 to 10 mm); jump when disturbed (Figs. 71, 73) - 22

21. White insects (up to 2 mm) that resemble tiny moths; often found on the undersides of host plant leaves, often associated with honeydew and sooty molds; flutter when disturbed (Figs. 60H, 72A) - WHITEFLIES

    Orange, brown, or black insects (up to 2 mm) that 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. 59B, 72B) . - THRIPS

22. Five to 10 segments in antenna; 2 to 5 mm long (Fig. 73) - PSYLLIDS

    Three segments in bristlelike antenna; 2 to 10 mm long (Fig. 71) - LEAFHOPPERS

KEY TO IMMATURE STAGES

BLOSSOM AND LEAF FEEDERS

1. Chewing mouthparts (Fig. 61B to D) (leaf removed or consumed by pest) - 2

   Mouthparts extended into tube or hairlike structure (Fig. 61F) (leaf may be distorted or discolored, but not consumed by pest) - 7

2. Insect within leaf mine, leaf gall, inwardly rolled leaf margin, or case made of plant material (Fig.74A to C) - 3

   Pest exposed on leaf - 5

3. Insect mining within leaf, leaving visible tunnels or leaf blisters (Fig. 74A) - LEAF-MINING CATERPILLARS OR MAGGOTS

   Not as above - 4

4. Tiny, whitish maggot(s) hidden within curled leaf margins (Fig. 74B) - MIDGE MAGGOTS

   Pest enclosed in a baglike, silken case enmeshed with pieces of leaves or needles (Fig. 74C) - BAGWORMS

5. Slime trail often noticed on damaged portion; soft-bodied, slimy animal, sometimes with helical shell (Figs. 59G; 66A,B). - SLUGS AND SNAILS

   No slime trail; worm shaped with paired legs - 6

6. Caterpillar with five to eight pairs of legs (Fig. 75A to B) - MOTH CATERPILLARS

   Caterpillar with more than eight pairs of legs (Fig. 75C) - SAWFLY CATERPILLARS

7. Pest mobile, usually with two "honey tubes" or "exhaust pipes" on abdomen (Fig. 76A to E) - APHIDS

   Mobility variable; no "honey tubes" or "exhaust pipes" on abdomen - 8

8. Microscopic pest usually associated with distorted plant growth; if not distorted, leaves may be scratched, brown, and/or curled - 9

   Not microscopic, or if microscopic, not associated with above symptoms - 10

9. Microscopic pest usually associated with distorted plant growth; three pairs of legs (Fig. 77A) - THREAD-LEGGED MITES

   Microscopic pest that causes leaves to appear scratched, turn brown, and curl; two pairs of legs (Fig. 77B) - RUST MITES MITES

10. 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. 78) - SPIDER MITES

    Not as above - 11

11. Very small, active, orange to yellow, spindle-shaped insect; feeding in buds, flowers, and on leaves (Fig. 79A to D). - THRIPS

    Not as above -12

12. Immobile (except newly hatched crawler stage); body adhering to plant surface so that legs are not visible - 13

    Mobile; legs visible - 15

13. Body covered with fluffy or "mealy," white wax secretions; older individuals with waxy strands around periphery (Fig. 80A to E) - MEALYBUGS

    Body not covered by mealy wax -14

14. Eggs usually laid under body of mother or young born live under mother (Fig. 81A) - SCALES

    Eggs inserted into leaf tissue and scattered on lower leaf surface; immatures often associated with whitefly adults (Fig. 81B) - WHITEFLIES

15. Body covered with white, powdery secretions - 16

    Body bare of secretions - 17

16. Slow moving; body coated with floury or "mealy" secretions (Fig. 80A to E) - MEALYBUGS

    Jumping insect covered with white, waxy filaments; associated with small, cicada like adult (Fig.82) - PSYLLIDS

17. Tiny, black or colorless, spiny nymphs (Fig. 83A,B) - LACE BUGS

    Nymphs not spiny - 18

18. Jumps when disturbed; body elongate (Fig. 84A) - LEAFHOPPERS

    Runs when disturbed; body oval in top view (Fig. 84B) - PLANT BUGS

STEM BORERS AND FEEDERS

1. Pest mobile - 2

   Pest immobile (except for first-instar nymph crawler stage) or moves very rarely - 6

2. Oval, round, or pear-shaped pest that may or may not be covered with waxy strands - 3

   Wormlike larva with variable number of legs - 5

3. Covered with woolly strands of wax; feeds only on conifers, usually near tips of branches; causes galling and distortion of branches (Fig. 85A) - ADELGIDS

   Not as above - 4

4. Covered with woolly secretion of wax; may feed on both roots and stems, may cause galls especially on roots (Fig. 85B) - WOOLLY AND GALL-FORMING APHIDS

   Tiny, flattened insect (crawler); not waxy or pear shaped; no cornicles; found in conjunction with immobile scale insects (Fig. 85C) - SCALE CRAWLERS

5. Body generally cylindrical, with eight pairs of legs; bores in stems (Fig. 86A) - MOTH CATERPILLARS

   Body flattened somewhat; legless or has three pairs of legs; bores in stems (Fig. 86B) - BEETLE LARVAE

6. Rarely moves once feeding is initiated; covered with cottony, waxy strands; feeds only on conifers, usually near tips of branches; causes galling and distortion of branches (Fig. 85A) - ADELGIDS

   Body adhering to plant surface so that legs are not visible; eggs usually laid under saclike body ofmother or young born live under mother (Fig. 85C) - SCALES

ROOT FEEDERS

1. Soft-bodied, grublike larva that strips off bark and chews out notches in roots (Fig. 87) - WEEVIL LARVAE

   Small insect with heavy, light, or practically nonexistent coat of woolly wax; feeds on stems and roots often causing gall-like swellings on roots (Fig. 85B) - WOOLLY or GALL-FORMING APHIDS

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