The thoracic glands of the pyrrhocorid Dysdercus cingulatus are described. They originate in the second maxillary segment and grow backwards with the salivary gland system. During post-embryonic development the gland nuclei increase in size but not in numbers. In each instar they enlarge, discharge their secretion, and shrink. The thoracic glands of ten other Heteroptera from eight families are described. All consist of large granular nuclei with little surrounding cytoplasm, most commonly arranged as a pair of elongated ductless glands lying parallel to the salivary ducts and attached distally to either the principal or the accessory glands. The thoracic glands are well supplied with tracheoles, but unlike other insects in which corresponding organs have been described, do not appear to have a nerve supply. The number of nuclei in each gland is surprisingly constant, being about 300 in almost all the species examined, the volume of the gland being greater in the larger insects by increase in the size of individual nuclei. The glands disappear very rapidly after the last moult.

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