Morphology of glands and ducts in the two-spotted spider-mite, Tetranychus urticae Koch, 1836.

Tetranychus urticae has three pairs of silk glands, an unpaired salivary gland, and (in males, at least) a pair of glandular ’tracheal organs’ . The silk glands on each si de empty into a corn mon duct. This duct can be opened and closed to the outside air at both ends. The tracheal organs contain labyrinthine air-channels.