The structure of the Spiracles of the cattle tick, Boophilus microplus

Abstract

The structures of the nymphal and adult spiracles of the tick, Boophilus microplus, have been examined by means of serial sections and a stereoscan electron microscope. Contrary to the views of recent writers, the functional openings of the spiracle have been found to be holes or aeropyles in the peripheral part of the spiracular plate of the adult tick. The ostium of previous writers is shown to be the ecdysial tube, which is present only in the spiracles of adult ixodid ticks. After the nymphal-adult ecdysis, the ecdysial tube is closed. There is thus no ostium in this stage, as has been claimed by previous writers who supposed that the chief or only route for gas exchanges between the atrium of the spiracle and the ambient air was through the so-called ostium. The ecdysial process of the spiracles of ticks is shown to be basically similar to the ecdysial process of the spiracles of certain insects such as scarabaeid larvae and the larvae of some Diptera-Cyclorrhapha.