Fig. 3.

Tracheal system of Schistocerca americana. Images are first instar abdomen (A) and head (C) and adult abdomen (B) and head (D) in a dorsoventral view. Note different scales for juvenile and adult images. A few tracheae (tr) and air sacs (as) are indicated, as well as antennae (ant) and spiracles (sp). In older, larger animals, respiratory structures make up a much greater fraction of the images, and tracheae are proportionally larger in adults. Also, air sacs are abundant in adult, but not first instar grasshoppers.