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What is a Water Stick?

Water sticks are a type of insect in the water scorpion group.  Water scorpions are large, aquatic true bugs in the insect order Hemiptera and family Nepidae.  They are common insects with a long tube (=respiratory siphon) that protrudes from the back end:

water stick, top view

Water stick, top view

The water sticks are a particular type of water scorpion, those in the genus Ranatra, and include species that are very long and narrow and similar in shape to walking sticks. These insects have long, thin legs with the front pair folding back on themselves in a praying mantid style raptorial (=grasping) leg:

Close up of water stick front end

Close up of water stick front end

Water sticks are sit-and-wait predators.  They cling to objects underwater (rocks, vegetation, etc), hold their legs out in front of their bodies, and wait for prey to swim by.  When prey comes near, a water stick will attempt to grab it with its raptorial forelegs.  If successful, it will use its forelegs to hold the captured animal in place and consume it.  The water stick’s short “beak” (visible above) protrudes from the front of the head and is used to inject chemicals that both paralyze and digest prey, liquefying the muscle inside the prey animal so that the water stick can suck up the resulting juices through its mouthparts.  Water sticks are known to eat small fish, tadpoles, and other aquatic insects, anything they can capture and subdue with their forelegs.

Water sticks are poor swimmers with legs rather ill-adapted to life in aquatic habitats.  You will most often find them clinging to vegetation just below the surface, sitting so that the tip of the posterior “snorkel” (i.e. the respiratory siphon) sits above the surface of the water.  In this position, the water sticks have constant access to air and can avoid making trips to the surface to breathe, allowing them to remain still and avoid detection by both predators and prey.  Water sticks can, however, dive below the surface for several minutes if disturbed.

You may find many water sticks together in one area (hundreds or thousands!), especially in low quality water.  Polluted waters are often oxygen poor and aquatic insects that breathe dissolved oxygen in the water are unable to survive there.  Water sticks are found in a variety of habitats and water qualities in part because they do not depend on dissolved oxygen and breathe at the surface instead.  As a result, they tend to be pollution-tolerant and are often found in polluted waters where very few other species live.

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