| 1. |
(a) One or two pairs of well-developed wings present, though often folded along body and inconspicuous |
Go to Couplet 2 |
| (b) Wings absent, or present only as small pads or scales less than half length of abdomen |
Go to Couplet 21 |
| 2. |
(a) Only the front pair of wings present |
Go to Couplet 3 |
| (b) Two pairs of wings present, hindwings may be concealed beneath protective forewings |
Go to Couplet 4 |
| 3. |
(a) Front wings hard, opaque, forming protective cover over abdomen, not used for flying |
Order COLEOPTERA |
| (b) Front wings membranous, not forming covers, used for flying |
Order DIPTERA |
| 4. |
(a) Front wings hard and opaque, at rest forming close-fitting covers for the transparent hindwings; front wings with no branching veins except sometimes just at the apex |
Go to Couplet 5 |
| (b) Front wings either transparent, or with branching veins over most of surface, or not forming close-fitting covers over hindwings |
Go to Couplet 7 |
| 5. |
(a) Mouthparts forming a cylindrical sucking rostrum beneath head, often folded between the forelegs; palps absent |
Order HEMIPTERA |
| (b) Mouthparts not forming a rostrum; palps present on mouthparts |
Go to Couplet 6 |
| 6. |
(a) Abdomen with prominent, pincer-like forceps at end; front wings much shorter than abdomen |
Order DERMAPTERA |
| (b) Abdomen without prominent, movable forceps; front wings usually as long as abdomen |
Order COLEOPTERA |
| 7. |
(a) Wings covered with microscopic, overlapping scales which easily rub off; mouthparts forming a coiled, sucking proboscis (sometimes absent) beneath the head |
Order LEPIDOPTERA |
| (b) Wings usually bare or hairy; mouthparts not forming a coiled tube |
Go to Couplet 8 |
| 8. |
(a) Abdomen usually with 3 long, flexible, segmented filaments at its rear end; if with two filaments then front wings much larger in area than hindwings |
Order EPHEMEROPTERA |
| (b) Abdomen usually without 3 long segmented filaments; if with 2 filaments (cerci) then front wings not larger than hindwings (a long central ovipositor may be present in some females but it is not segmented as in the filaments of Ephemeroptera) |
Go to Couplet 9 |
| 9. |
(a) Mouthparts forming a straight, cylindrical rostrum, sometimes concealed between forelegs; palps absent |
Order HEMIPTERA |
| (b) Mouthparts not forming a true rostrum, sometimes elongate but then 2 or more palps are present |
Go to Couplet 10 |
| 10. |
(a) Forewings thicker and more opaque than hindwings and forming a protective cover for them |
Go to Couplet 11 |
| (b) Both pairs of wings of similar texture |
Go to Couplet 14 |
| 11. |
(a) Forelegs armed with spines and modified for seizing prey; prothorax very long |
Order MANTODEA |
| (b) Forelegs not modified for seizing prey; prothorax usually not long |
Go to Couplet 12 |
| 12. |
(a) Body long and narrow, stick- or leaf-like in form; hindlegs not modified for jumping |
Order PHASMATODEA |
| (b) Body long and narrow, the hindlegs modified for jumping |
Go to Couplet 13 |
| 13. |
(a) Thorax covering head when insect viewed from above; hindlegs not modified for jumping |
Order BLATTODEA |
| (b) Head visible when insect viewed from above; hindlegs with femora enlarged for jumping |
Order ORTHOPTERA |
| 14. |
(a) Antennae minute, bristle-like, shorter than the width of an eye and having only 5-8 segments; wings flat, unfolded |
Order ODONATA |
| (b) Antennae normal, longer than width of an eye and having more than 8 segments; wings often folded or pleated when at rest |
Go to Couplet 15 |
| 15. |
(a) Wings with many veins and cross veins forming a close network over much of wing surface; two cerci sometimes present at tip of abdomen |
Go to Couplet 16 |
| (b) Cross veins few in number; cerci absent |
Order HYMENOPTERA |
| 16. |
(a) Wings deciduous, with a fracture line across their base; veins thickened along the leading edge of wing |
Order ISOPTERA |
| (b) Wings not deciduous; all wing veins of about equal thickness |
Go to Couplet 17 |
| 17. |
(a) Two segmented cerci present at tip of abdomen; body and wings never hairy |
Order PLECOPTERA |
| (b) Cerci absent, or small and unsegmented; body and/or wings often hairy |
Go to Couplet 18 |
| 18. |
(a) Mandibles absent; moth-like insects with hairy wings |
Order TRICHOPTERA |
| (b) Mandibles present; usually not moth-like |
Go to Couplet 19 |
| 19. |
(a) Head drawn out into an elongate beak with mouthparts at apex |
Order MECOPTERA |
| (b) Head not noticeably beak-like |
Go to Couplet 20 |
| 20. |
(a) Wing veins forking just before they reach edge of wing |
Order NEUROPTERA |
| (b) Wing veins not forking just before they reach the edge of wing |
Order MEGALOPTERA |
| 21. |
(a) Abdomen terminating in 3 long segmented filaments |
Order THYSANURA |
| (b) Abdomen with none or 2 terminal segmented filaments (a long central ovipositor may be present in some females but it is not segmented) |
Go to Couplet 22 |
| 22. |
(a) Abdomen terminating in a pair of stout, pincerlike forceps |
Order DERMAPTERA |
| (b) Abdomen without terminal forceps |
Go to Couplet 23 |
| 23. |
(a) Mouthparts forming a cylindrical rostrum beneath the head; palps absent |
Order HEMIPTERA |
| (b) Mouthparts not a rostrum; palps present |
Go to Couplet 24 |
| 24. |
(a) Abdomen constricted to a narrow waist just behind the forebody |
Order HYMENOPTERA |
| (b) Abdomen without a narrow waist |
Go to Couplet 25 |
| 25. |
(a) Prothorax much longer than mesothorax, sometimes concealing the head when viewed from above |
Go to Couplet 26 |
| (b) Prothorax small, not much longer than mesothorax, never concealing the head |
Go to Couplet 27 |
| 26. |
(a) Body broad and flattened; hindlegs not modified for jumping |
Order BLATTODEA |
| (b) Body more or less cylindrical; hindlegs with enlarged femora for jumping |
Order ORTHOPTERA |
| 27. |
(a) Large, elongate, camouflaged stick- or leaf-like insects |
Order PHASMATODEA |
| (b) Small ant-like insects; body not markedly elongate, not camouflaged |
Order ISOPTERA |