73 

 Bentinck: Structure and Classification 



obese, or flattened and oval, with or without appendages 

 and distinct sclerotized head capsule. Larvae .... 21 



— Body completely enclosed in a hard, capsulelike case 

 or puparium, or mummy like with appendages free or 

 fused to the body covering. Pupae 29 



21. Thorax with 3 pairs of legs 22 



— Thorax without legs 26 



22. Underside of abdomen with at least 2 pairs of fleshy 

 prolegs tipped with many small hooks. Caterpillars 

 (in part) LEPIDOPTERA 



■ Abdomen without prolegs 23 



23. Anal segment with a pair of hook-bearing appendages; 

 antennae inconspicuous, 1-segmented; eyes consisting 

 of a single facet; tracheal gills, if present, seldom 

 confined to lateral margins; usually living in silken 

 cases which may have vegetable or mineral matter 



incorporated in their construction 



(in part) TRICHOPTERA 



• Anal segment without hooks; or if hooks are present, 

 then antennae consist of more than 1 segment, eyes 

 are of more than 1 facet, and tracheal gills are lateral 

 24 



24. Mandibles and maxillae united to form long straight 

 or slightly recurved suctorial tubes; abdomen with 

 segmented gill appendages folded beneath; size small, 



10 mm. or less; feed on fresh-water sponges 



(in part) NEUROPTERA 



— Maxillae not united with the mandibles; mandibles if 

 suctorial are strongly curved; gill appendages, if 

 present, seldom segmented and never folded beneath 

 abdomen 25 



25. Abdomen with 7 or 8 pairs of segmentally arranged 

 lateral filaments or gills; ninth segment with a pair of 

 hooked anal feet or with a single long filament. Hell- 

 gramites (in part) MEGALOPTERA 



— Abdomen usually without such lateral filaments; but, 

 when present, with hooked anal feet absent, or located 

 on tenth segment and 4 in number, or with no median 

 filament. Beetle larvae (in part) COLEOPTERA 



26. Head capsule distinct, at least anteriorly 27 



■ Without a distinct, sclerotized head capsule 28 



27. Abdomen with gills or a breathing tube at posterior end. 

 Mosquito larvae, etc, (in part) DIPTERA 



— Abdomen without terminal gills or a breathing tube. 

 Weevil larvae (in part) COLEOPTERA 



28. Larvae elongate, more or less cylindrical, or spindle- 

 shaped, or peg-shaped with anterior end pointed and 

 posterior end blunt. Maggots, crane fly larvae, etc. 

 (in part) DIPTERA 



— Larvae not as above; less than '2 mm. in length; 

 parasitic (in part) HYMENOP1 IK \ 



29. All appendages invisible, tin- pupa enclosed 

 hardened, barrel-shaped ospsule with segmental simu- 

 lations (Coarctate pupae) (in part) DIPTERA 



— Appendages visible, either free or fused t<< pupal 



(if enclosed in a silken or hardened ooi oon or <a»e, 

 this should be removed to see the pupal i ban* tors) 

 80 



30. Appendages free, though sometimes held in a fixed 

 position, mummy 1 1 kf (Exarate type) 81 



— Appendages fused to the body wall, forming a continu- 

 ous covering (Obtect type) 



31. Abdomen constricted at base, narrow 1) joined (<» thorax 

 (in part)" HYMENOPTERA 



— Abdomen broadly joined to the thorax 32 



32. Thorax with only 1 pair of wing pads 



(in part) DIPTERA 



— Thorax with 2 pairs of wing pads 33 



33. Antennae usually 1 1-segmented, pads of front wings 

 thickened (in part) COLEOPTKW \ 



— Antennae always with 12 or more segments; pads of 

 front wings not appearing like leathery wing covers . 34 



34. Mandibles curved, base stout, usually projecting for- 

 ward and crossing each other; usually in cases or webs 

 constructed by the larva (in part) TRICHOPTERA 



— Mandibles broad and stout, never overlapping or cross- 

 ing each other 35 



35. Size small, 10 mm. or less; cocoon spun in protected 

 spots near stream above ground 



• ■ (in part) NEUROPTERA 



— Size larger, 12 mm. or more; pupae in burrows in ground 

 or wood (in part) MEGALOPTERA 



36. A pair of short breathing tubes present anterodorsally 

 and a pair of leaflike gills at tip of abdomen. Mosquito 

 pupae (in part) DIPTERA 



— Without anterodorsal or posterior breathing tube and 

 without leaflike gills (in part) LEPIDOPTERA 



REFERENCES 



BRUES, C. T., A. L. MELANDER, and F. M. CARPENTER 

 1954. Classification of Insects. Bull. Mus. Comp. Zool., 

 73: v + 917, 1219 figs. 

 ESSIG, E. O. 



1942. College Entomology. New York: Macmillan. vii + 900 

 pp., 308 figs. 



