Bugs

Classification

Order of Insects

Synonyms

Rhynchota, Hemiptera

General Information

Among the 30,000 species of bugs of the suborder Heteroptera, two families have obtained medical importance due to their periodic blood-sucking activity which allows transmission of pathogens (Table 1): the Reduviidae (predacious bugs) including the Triatominae (kissing bugs) with wings, and the Cimicidae (bedbugs, Fig. 1A) without wings. Both groups are dorsoventrally flattened bugs and feed on the blood of their hosts by means of their stylet-like mouth parts, which are included inside an eversible proboscis (Fig. 2) located at the tip of their head; furthermore, “stinking glands” which open behind the 3rd-6th abdominal tergit (in juvenile bugs) or alongside the metathorax (in adults) are characteristic. The hemimetabolous development of the Rhynchota includes five nymphal instars (Fig. 1B).

Life Cycle

  

Fig. 1. Life cycle stages of the wingless Cimicidae (A, Cimex lectularius, bedbug) and the Reduviidae (B, Rhodnius prolixius) in dorsal view. 1 The eggs are laid in batches by Cimex and mostly singly by Rhodnius in the crevices of bed frames, walls, or similar household sites. 2 The larvae (nymphs I) which hatch from the eggs are wingless and feed (as do all other stages) by sucking the blood of humans, and also many other mammals. 3–7 Five molts of the nymphal instars are needed to reach the sexually mature female or male stage (7); in Reduviidae typical fore- and hindwings are eventually formed, but Cimicidae remain wingless in all stages.

Important Species

Table 1. Some common parasitic bugs

  

Fig. 2. SEM micorgraph of the ventral side of a reduviid bug showing the attached, but protrudible sucking-tube. × 30