Damselflies, like dragonflies, pass through a larval stage that develops in water. As the larva grow in size, it moults many times before becoming an adult. It is a voracious carnivore, catching and eating its prey that includes small aquatic insects and their larvae, small crustaceans, fishes and even worms.
Tang Hung Bun LINK, an avid dragonfly enthusiast, managed to document the larva of the Look-alike Sprite (Pseudagrion australasiae) catching and eating a small fish alive (below). An uncommon damselfly in Singapore (above), the larva was lurking among the water-weed waiting for an unsuspecting prey when the fish appeared.
As Hung Bun describes it, “Once the damselfly larva senses something moving below it, it quickly turns its body around and makes its first, but unsuccessful, attempt to catch the fish with its elbowed labium [extension of a specialised lower lip]. If you watch the clip carefully, you would be able to see the fish swimming away from the extended labium of the larva. Soon the fish comes back and this time the damselfly larva manages to secure its meal. The action is too fast for my camera (running at 25fps) to capture clearly. The damselfly larva then slowly consumes the whole body of the fish, except the head.” This it does with its powerful mandibles.
Note that the larva is 23 mm long as compared to the 7 mm long fish.
In the video below, a group of larvae of the Variable Sprite (Argiocnemis rubescens) (above), another uncommon damselfly, is foraging in a pond in a forested area. One of the larvae managed to catch a mosquito and consumed it in about 20 minutes.
Note: Video clips and image of Variable Sprite by Tang Hung Bung; image of Look-alike Sprite by Lena Chow.