
Source: Wikimedia Commons
Laccotrephes japonensis
An aquatic bug that waits in ambush underwater with the tip of its long abdominal breathing tube at the surface. The Japanese name comes from the way it moves its front legs like someone beating a drum, and it takes poor water quality fairly well.
Laccotrephes japonensis is a brown, spindle-shaped water bug of 30-35 mm that lives in shallow water such as streams and rice paddies. A long breathing tube at the tip of the abdomen is held with its end at the surface while the bug waits underwater for prey. It seizes fish, other aquatic insects and tadpoles with its raptorial front legs, injects digestive fluid through its stylets and sucks out the dissolved tissue. The Japanese name comes from the way it moves its front legs, likened to beating a drum. Picked up, it draws in its legs and feigns death. Eggs are laid from May to August, the female placing them a few or up to ten at a time in soil or moss at the waterside, each egg carrying about ten respiratory filaments. The larvae reach adulthood in about two months through five moults. Around November they overwinter on land and in the water, and the bug lives two to three years.
Source: Wikipedia (CC BY-SA 4.0)
The Water Scorpion lives 2-3 years.
The Water Scorpion grows to 30-35mm.
Origin
Japan (Honshu south of the Tsugaru district of Aomori, Shikoku, Kyushu, Tsushima and the Nansei Islands north of Okinawa Island)
Lifespan
2-3 years
Size
30-35mm
Temperature
Edited & verified by: BreederDirect editorial team
The taxonomic, regulatory, and husbandry data on this page are compiled and verified against the authoritative primary sources below.
Accepted name: Laccotrephes japonensis Scott, 1874
Authority databases: GBIF
Nomenclature follows global taxonomic authority databases.
Sources: CITES Appendices (species not listed)
Regulations may change. Always verify the latest information with the relevant authorities.
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20〜28℃
Humidity
60〜80%
Small fish, tadpoles, aquatic insects and terrestrial insects
Set the depth so that the breathing tube reaches the surface from the bottom, and if the water is deeper add plants or twigs to climb. Around November it overwinters both on land and in the water.
The laying season runs from May to August. The female places eggs, each with about ten respiratory filaments, in soil or moss at the waterside, a few or up to ten at a time. The larvae reach adulthood in about two months through five moults.
It is predatory and reacts to movement, so fish or shrimp housed with it become food. It will also eat its own kind, so larvae are safer kept separately.
It lives two to three years, which is long for a water bug. The larval period is short, about two months, during which it moults five times.
Unlike the giant water bug it does not need a constant supply of aquatic prey; dropping suitable small insects on the surface will raise both larvae and adults. It also takes poor water quality fairly well and is considered a good first water bug. It flies, so keep the container covered. Note that the related Laccotrephes grossus of the Yaeyama Islands is a nationally protected species and may not be collected. The English name "water scorpion" covers the whole family Nepidae, including the slender water stick insects, so English-language care information may describe a different genus; confirm the scientific name Laccotrephes japonensis.
Beginner. This is a beginner-friendly species. No special equipment or experience is required, and it can be kept successfully with basic care setup.
The average lifespan of Water Scorpion is 2-3 years. With proper care and nutrition, they can live a long and healthy life.
Water Scorpion typically reaches 30-35mm as an adult. Size may vary depending on care conditions and individual genetics.
Water Scorpion feeds on: Small fish, tadpoles, aquatic insects and terrestrial insects. Aim for a balanced diet with appropriate feeding frequency.
The price of Water Scorpion varies significantly depending on bloodline, size, captive-bred generation, and sex. Check our market price page for the latest pricing information.
Last updated: September 16, 2026