alternative definition added about 15 years ago by Andy Deans
The movements of the pretarsus are produced the musculus retractor unguis (MRU) in all insects (Snodgrass, 1935), which originates within the tibia and femur and has a long tendon that inserts through the terminal tarsomer onto the unguitractor. Contraction of muscle pulls the unguitractor inward, and causes downward flexion of the claws.
Reference: Gladun, D. V. 2008. Morphology of the pretarsus of the sawflies and horntails (Hymenoptera: 'Symphyta'). Arthropod Structure & Development 37:13-28.
Cross reference:
None provided.