Specimen Showcase | Master of Trap
- Hong Kong Biodiversity Museum
- Apr 9
- 4 min read
The word “lion”🦁 implies respect as it refers to an apex predator fearing few other creatures. Today, we will talk about a special type of lion, the antlions of the genus 𝘔𝘺𝘳𝘮𝘦𝘭𝘦𝘰𝘯. (Linnaeus, 1767). As we will see, this group of insects is as ferocious as its mammalian counterpart. This genus of Neuroptera, an order of insects also including lacewings and the surprising mantidflies, is found in various habitats and regions of the world, including open woodlands, scrub grasslands, and dry sandy areas in tropical regions, such as Thailand, Indonesia, Hong Kong, and so on☀️.
The antlion larvae, with a size of 1.2 cm, are voracious predators, especially when it comes to ants🐜, which constitute the majority of their diet. This “preference”, however, is involuntary, but rather the results of the commonness and abundance of ants in the areas inhabited by antlion’s larvae. In fact, if given proper opportunities, the diet can also include various other types of arthropods including, but not limited to beetles, small spiders and ticks🍽️.
To capture its prey, the larvae would not only sit and wait, but also build a characteristic death trap – in the shape of a funnel pitfall. The larvae can, however, be very picky when selecting the site to build the trap. This location needs to have high availability of dry and sandy soil, high availability of prey, and relatively low intraspecific competition with few other antlions around. Upon making their choice, the larvae would begin to dig pits starting from a circular groove by throwing sand away🕳️, using its mandibles like a shovel. Afterwards, they would gradually move down in a spiral from the circumference towards the centre, making the pit deeper and deeper. Eventually this will create a funnel of death with a single antlion waiting patiently at the bottom - a scene worthy of a Star Wars movie.
When the unlucky prey falls straight toward the base of the trap, the antlion larvae would rapidly close its sickle-shaped jaw and inject paralysing venom as well as digestive enzymes into the victims. In a few minutes, the soft part of the victims would become nutritious meat soup, ready for the larvae to suck and drink. Even if the prey is lucky enough to get a grip on the edge, the larvae would violently throw sand or soil on it to destabilize it, hence making the prey inevitably fall. Some species, such as 𝘔𝘺𝘳𝘮𝘦𝘭𝘦𝘰𝘯 𝘩𝘺𝘢𝘭𝘪𝘯𝘶𝘴 (Olivier, 1811), would even actively follow the escaping prey, climb the pit wall, and seize it, making escape very unlikely, with an impressive capture success rate of over 95%.
Despite sit-and-wait predation being energy conserving with a high success rate, relying on the pitfall can be troublesome when it comes to larvae development. If the pitfall is constantly destroyed due to external factors (e.g. weather, large animals), the larvae would continue to build it up again and again, which is very time and energy consuming🚧. Under such stress, the antlion larvae would begin to decrease their respiration rate while ambushing to save up energy in case it has to rebuild the pitfall again. The constant destruction and rebuilding of pitfall would slow down the establishment of energy reservation that is necessary for metamorphosis, hence stretching the range of larvae development time from three months to up to 2 years! Such prolonged time would expose the antlion larvae to risks such as cannibalism or being attacked by parasitoids.
When compared to their larvae, which have a fusiform body with a very plump abdomen, adult antlions are much more nice-looking. The adults possess two pairs of long, narrow, multi-veined wings and long, slender abdomen, with an appearance that highly resembles dragonflies or damselflies. Still it is quite easy to distinguish them as adult antlions typically have a pair of apically clubbed antennae.The sizes of the adult antlions vary substantially between species, with body lengths ranging from 10 mm to 30 mm, and their forewing length ranging from 10 mm to 70 mm; a 6-times difference! Despite having a pair of relatively large wings, most of them are feeble fliers and are normally found fluttering around at dusk or after dark. Good luck trying to find them when the sun is up, as they are rarely active during day time. Additionally, like many other insects, antlions have a rather short adult stage, lasting about a month. During this time, instead of eating ants or other small insects like their larvae, they would nourish themselves with nectar and pollen🌷.
Curious to see by yourself? Come visit the Hong Kong Biodiversity Museum and discover more fascinating exhibits. If you enjoy this post, feel free to share it with your friends and follow us for more posts.
Text: Felix Tan
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