Giant Water Bug

Looks how to spot one

Exoskeleton

Giant water bugs have a flattened, oval body that is brown or olive, with a tough exoskeleton. The front legs are shaped like pincers for grabbing prey, while the hind legs are flattened and fringed with tiny hairs to help them swim. At the tip of the abdomen they have a short, snorkel-like tube called a siphon that they poke above the water to breathe.34

Personality what they are like

Giant water bugs are aggressive predators even towards prey much larger than themselves, but they are not typically active swimmers, they prefer to lie still and ambush. They should be handled with extreme caution because they can deliver a very painful bite with their piercing mouthparts, which also inject venomous saliva. In the tank they move little and spend most of the time perched just below the surface.357

Daily activity how busy a day looks

Low. They are sedentary ambush hunters and do not need a large swimming area. However, the tank must have perches or objects that reach close to the water surface so they can breathe easily. They will not exercise actively.57

Grooming and care the hands-on bits

Water should be changed or cleaned regularly, especially after feeding. Filtration is optional and aeration is not needed. The tank must have a tight, ventilated lid to prevent escape. No substrate is required, but floating cork bark, plastic plants and a few small rocks provide hiding places.58

Home where they are happiest

A single adult needs at least 1 litre of water. The tank should have sticks or plant stems that protrude at least 10 cm above the water line to serve as egg-laying sites and perches. The water bug needs to be able to reach the surface easily to breathe through its siphon. Temperature should be kept between 22 and 26 °C, though they tolerate 15-30 °C. They cannot climb smooth surfaces, but a secure lid is still essential.5

Food basics what goes in the bowl

Feed live prey such as crickets, cockroaches, mealworms, water boatmen and backswimmers. Adults can be given prey dropped onto the water surface or offered with forceps. Feed at least once a week; two to three substantial meals a week is ideal. A well-fed bug has a rounded underside; a strongly keeled belly indicates it needs feeding. Avoid using wild-caught insects as they may carry pesticides or parasites.58

Company who they like around

Keep singly unless you are trying to breed them. They are cannibalistic, especially if crowded or underfed. Males are the primary carers for eggs; in some species the female glues eggs onto the male's back, and in others the male guards eggs laid on vegetation.53

The story where it all began

Giant water bugs have been kept by dedicated hobbyists for many years, particularly in Japan, where species like Kirkaldyia deyrolli and Lethocerus indicus are traded in pet shops. They are also valued as a food source and flavouring in parts of Southeast Asia. Because of their dramatic predatory behaviour and the unusual paternal care of the males, they are popular among insect keepers who want a fascinating, low-maintenance aquatic invertebrate.13