Elateriformia (Coleoptera) Larvae
Trachyines are widely distributed.
Larvae of Trachyini are leaf-miners.
Böving, A. G. and Craighead, F. C. (1931). An illustrated synopsis of the principal larval forms of the order Coleoptera. Entomologica Americana (New Series) 1: 1–351, 125 pls.
Lawrence, J. F. (1991). Buprestidae (Buprestoidea), pp 386–388 in Stehr, F. W. (ed.), Immature Insects. Vol. II. Kendall Hunt: Dubuque, Iowa.
Body. Length less than 3 mm. Body not broadly ovate and strongly flattened; relatively straight or only slightly curved ventrally; strongly flattened; body, as viewed from above elongate and more or less parallel-sided. Vestiture consisting of fine hairs or setae only. Dorsal surfaces very lightly pigmented or sclerotized; generally smooth. Ventral surfaces very lightly pigmented.
Head. Head prognathous or slightly declined; strongly retracted; not concealed from above by prothorax; narrower than thorax; not forming sclerotized, serrate, wedge-like plate. Head capsule not strongly depressed and wedge-like anteriorly; posterior edge of head capsule distinctly emarginate. Median epicranial region without longitudinal furrow. Epicranial stem absent or very short. Frontal arms present; V-shaped or U-shaped; not joined anteriorly by transverse line; bases of frontal arms contiguous. Median endocarina short or long, extending between frontal arms (epicranial stem absent). Paired endocarinae absent or coincident with frontal arms. Number of stemmata two. Number of antennal segments two. Ratio of antennal length to head width less than 0.15. Sensorium(a) on preapical antennal segment apparently absent in antennae (usually 1- or 2-segmented) with apical sensorium. Antennal base without eversible membranous lobe. Frontoclypeal suture distinct. Labrum separated from head capsule by complete suture. Epipharyngeal rods absent. Mouthparts not forming sucking tube. Mandibles symmetrical; opposable, at least slightly curving mesally at apex; not approximate, diverging and longitudinally divided; broad and stout or more or less wedge-like; without groove or perforation. Accessory ventral process of mandible absent. Incisor edge of mandible simple. Mesal surface of mandibular base simple or slightly expanded. Mandibular mola absent. Ventral mouthparts strongly protracted. Cardines or maxillary bases separated from each other by labium. Stipes longer than wide. Maxillary articulating area absent. Maxilla with single, fixed mala. Mala or galea consisting of a single segment. Apex of mala simple, not cleft; or galea rounded or truncate; or galea setose or spinose. Inner apical angle of mala simple. Number of segments in maxillary palp two. First segment of maxillary palp without digitiform appendage. Labium consisting of single plate. Mentum, postmentum or labial plate completely or almost completely connate with maxillae. Postmentum or labial plate subquadrate or trapezoidal, with blunt posterior edge. Number of segments in labial palp zero. Hypopharyngeal bracon present. Hypopharyngeal sclerome absent. Hypostomal region present (separating labium from thorax). Hypostomal rods present (1 pair); moderately long but not extending to posterior edge of head, or extending to posterior edge of head; diverging posteriorly. Ventral epicranial ridges absent. Gula wider than long, or longer than wide; gular sutures separate. Gula or gular region separated from labium by suture. Occipital foramen not divided by tentorial bridge.
Thorax. Prothorax not or only slightly wider than abdomen; not longer than meso- and metathorax combined. Thoracic terga without patches of asperities; without rows of asperities or carinae. Protergum without sclerotized plates, or with 1 or more sclerotized plates. Meso- and metaterga without sclerotized plates. Thorax without well-developed lateral tergal processes. Prosternum without armature. Thoracic legs absent or represented by non-articulated lobes or processes. Number of segments in mesothoracic leg zero. Number of segments in mesothoracic leg five or fewer including pretarsus (claw). Thoracic spiracles cribriform; not placed at ends of spiracular tubes.
Abdomen. Ratio of length of abdomen (without appendages) to length of thorax more than 2.0. Number of visible abdominal segments ten. Abdominal terga not extending laterally beyond edges of sterna; without patches of asperities; without rows of asperities. Abdomen without well-developed lateral processes. Abdominal tergum 3 without transverse dorsal folds or lobes; simple, not divided into transverse dorsal folds or lobes. Paired abdominal glands (openings or porous plates) absent. Dorsal, balloon-like tracheal gills absent. Long and narrow, lateral gills absent. Abdominal sterna without patches of asperities; without rows of asperities. Paired ventral prolegs (or asperity-bearing ampullae) absent. Ventral abdominal gill tufts absent. Abdominal tergum 8 without special armature. Abdominal apex without respiratory chamber. Abdominal segment 9 excluding appendages as long as or slightly longer than segment 8. Abdominal tergum 9 not forming articulated plate; completely dorsal; without paired processes or urogomphi; without median process or terminal disc. Abdominal sternum 9 partly or entirely exposed; simple or apparently absent; not enclosed by sternum 8. Abdominal apex without hinged operculum. Abdominal segment 10 without oval lobes separated by longitudinal groove; distinct and visible from above; without asperated, tubular holdfast organs. Paired pygopods on segment 10 absent. Anal region posteriorly or terminally oriented. Anal gill tufts absent. Anal hooks absent. Anterior abdominal spiracles cribriform. Abdominal spiracles not placed at ends of spiracular tubes. Eighth abdominal spiracles functional and about the same size as others on abdomen; abdominal spiracle 8 lateral or dorsolateral, facing laterally.
Illustrations. • Trachys.
The interactive key provides access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting specified attributes, and summaries of attributes within groups of taxa.
Cite this publication as: ‘Lawrence, J.F., Hastings, A.M., Dallwitz, M.J., Paine, T.A., and Zurcher, E.J. 1995 onwards. Elateriformia (Coleoptera) larvae: descriptions, illustrations, identification, and information retrieval for families and subfamilies. Version: 9th October 2005. http://delta-intkey.com’.