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The walkingstick, Anisomorpha buprestoides, has two defensive glands in its thorax from which it ejects an aimed spray when disturbed. Contact stimulation is the usual trigger for the discharge, but birds may elicit the spray by merely approaching the insect. The secretion proved effectively deterrent to ants, predaceous beetles, mice, and blue jays, but not to an opossum.
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Thomas Eisner (1965) studied this question.
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