Three laboratory experiments demonstrated that (I) larvae were able to detect patches of high prey density in small aquaria; — (2) an immobile foraging mode was adopted when prey were abundant, and an active mode when prey was absent and larvae were starved; and — (3) larvae learned to prey on dead Chaoborus larvae (Dipt.) after 2 days "training”. Some larvae consumed dead Chaoborus larvae without previous training. — The observations indicate that A. juncea larvae are versatile predators, capable of modifying their foraging behaviour.