PLATE 1.26. QUEEN PROTHORACIC SPIRACLE

Top. Prothoracic spiracle, which lies beneath the spiracular lobe, or hairy plate (arrow) (the head is to the top left of this oblique view). The forewing base is visible (upper right). This spiracle is protected by the spiracular lobe and shrouded with body hairs, which must be removed, as in the other micrographs in this plate, before the spiracle and its interior can be observed. (x 56)

BOTTOM LEFT. Portion of the spiracular lobe, the atrium of this spiracle, and its immediate interior. This area is revealed when the hairs are removed from the thorax and a superficial slice of cuticle is taken from this region. (x 1,500)

MIDDLE RIGHT. Close-up of the tracheal atrium revealing the airway without any of its cuticular overcoats. The inner wall of the atrium has cuticular ridges from which project small spines or hairs, which support the integumental "pocket" concept of the atrium. The tracheal opening has been removed. (x 300)

BOTTOM RIGHT. Higher magnification of the cuticular hairs and ridges of the atrium of the prothoracic spiracle. The cuticular reticulum extends along the floor of the atrium. (x 1,200)