Figure 2. Lateral diagrams of anterior internal structures of a highly deriveddipteran larva. A. Note position of crop and salivary glands. B. Note the position of thewing disc in relation to the mouthparts and brain. C. The anterior part of the mouthparts, the“mouth hook”, is decorated by a number of teeth both on the hook and on the nub. Thesenumber from 0 – 12 depending on the species and developmental stage e.g. in D.