What Bug Is That? The guide to Australian insect families.

Logo: What Bug Is That? Logo: Taxonomy Research & Information Network

Identify families

Adult males

    • Tarsi 5-segmented, ending in a pair of strong claws; tarsi without sensory spots; antennae 6–7-segmented. 2
    • Tarsi either 2–4-segmented with neither claws nor sensory spots; or 4-segmented with weak, claw-like structure and sensory spots; or 5-segmented with very weak pair of claws and sensory spots; antennae 4–7-segmented. 3
  2. (1)
    • Prementum free with short palps; CuA1 short, extending about to middle of wing; antennae 7-segmented with lateral flabellum on 3rd and 4th segments; fossil species only. Mengeidae
    • Prementum fused to hypopharynx; CuA1 extending almost to edge of wing (Fig. 36.8A); MA strongly developed and with anterior branch present; antennae 6-segmented with lateral flabellum on 3rd–4th or 3rd–5th segments (Fig. 36.9A). Mengenillidae
  3. (1)
    • Tarsi 2-segmented, without claws; antennae 4-segmented with lateral flabellum on 3rd (Figs 36.8E, F). Elenchidae
    • Tarsi 3–5-segmented, if 5-segmented ending in very weak claws; antennae 5–7 segmented with lateral flabellum on 3rd, 3rd–4th, 3rd–6th or 3rd, 5th and 6th segments. 4
  4. (3)
    • Tarsi 3-segmented; antennae 6–7-segmented with lateral flabellum on 3rd; 3rd–4th or 3rd–6th segments. Halictophagidae
    • Tarsi 4–5-segmented; antennae 4–7-segmented with lateral flabellum on 3rd, 3rd–4th or 3rd, 5th and 6th segments. 5
  5. (4)
    • Mandibles absent; tarsi either 5-segmented with weak claws or 4-segmented and with or without a weak claw-like structure; tarsi with sensory spots; antennae 5–7-segmented with lateral flabellum on 3rd and 4th segments (Fig. 36.8B). Corioxenidae
    • Mandibles present; tarsi 4-segmented, without claws or sensory spots; antennae 4–7-segmented with lateral flabellum on 3rd or 3rd, 5th and 6th segments. 6
  6. (5)
    • Antennae 7-segmented with lateral flabellum on 3rd, 5th and 6th segments; maxillary base large; Neotropical. Bohartillidae
    • Antennae 4–7-segmented with lateral flabellum on 3rd segment only; maxillary base small. 7
  7. (6)



    • Free-living; larviform, with eyes, legs and antennae (Fig. 36.2). Mengenillidae
    • Parasitic in host and neotenic with only the cephalothorax protruding through the host cuticle during adult stage; eyes, legs and antennae absent (Fig. 36.4). 2
  2. (1)
    • Brood canal opening apical (Fig. 36.4A); ventral side turned towards host, parasites of Heteroptera. Corioxenidae
    • Brood canal opening ventral and at the junction of head and thorax (Figs 36.4B-H), ventral side turned away from host. 3
  3. (2)
    • Head half or more as long as cephalothorax; dorsal side not membranous (Figs 36.3, 36.4F, G); cephalothorax semi-circular, not bell-shaped; abdominal segments 1–5 each with genital aperture; parasites of Hemiptera (Auchenorrhyncha and Heteroptera), Diptera, Orthoptera and Blattodea. Halictophagidae
    • Head less than half as long as cephalothorax, or dorsally membranous and raised above host abdominal segments; cephalothorax round, bell shaped; abdominal segments 3–6 each with genital aperture, or segments 2–3 each with 1–5 or more than 5 genital apertures. 4
  4. (3)
    • Metathorax with functional spiracle; cephalothorax elongated; parasites of Heteroptera; South-East Asia. Callipharixenidae
    • Metathorax without functional spiracle; cephalothorax not so elongated (Figs 36.4B-F). 5
  5. (4)
    • Cephalothorax sclerotised and lying close to host abdominal segment; opening of brood canal slit-shaped (Figs 36.4B,C, 36.7D); abdominal segments 3–6 each with genital aperture; parasites of Hymenoptera. Stylopidae
    • Cephalothorax membranous and raised (Figs 36.4D-F); opening of brood canal wide. 6
  6. (5)
    • Cephalothorax with hook-like projections behind spiracles; opening of broad canal crescent-shaped (Fig. 36.4D); abdominal segments 2–3 each with more than 5 genital apertures; opening of brood canal; parasites of Mantodea and Orthoptera. Myrmecolacidae
    • Cephalothorax without hook-like projections (Fig. 36.4E,F); opening of brood canal not crescent-shaped; abdominal segments 2 and 3 each with 1–5 genital apertures; parasites of Hemiptera (Auchenorrhyncha). Elenchidae


Interactive keys to Strepsiptera are currently unavailable. Dichotomous keys from The Insects of Australia (Second Edition, 1991) have been provided until interactive ones are ready. These keys are presented as they originally appeared; no attempt to update them or the classification has been made.

Families in bold do not occur in Australia.