Water Treader

What is water treader?

A water treader is any insect belonging to the family Mesoveliidae (order Heteroptera). These are small, slender insects that typically measure 5 millimetres (0.2 inches) or less in length and are generally yellowish or greenish in colour.¹²

Water treaders are predaceous and are most commonly observed on floating vegetation or on the surface of the water, though they are also found at the edges of ponds. While they are distinct from the family Gerridae—commonly known as water striders—both groups are part of the broader category of semiaquatic bugs that utilize the water’s surface film for support.¹³⁴²

How do insects like water treaders walk on water without sinking?

Insects like water treaders are able to walk on water because they are supported by the surface tension of the water, which acts like a stretched elastic membrane.⁷

Several physical adaptations allow these insects to utilize this phenomenon:

• Body Size and Weight: Water treaders have small, slender bodies with very little bulk, which minimizes the force they exert on the water’s surface.³
• Leg Structure: They possess long, thin middle and hind legs that spread their weight across a larger area. The tarsus (the end segment of the leg) of each limb causes only a slight, shallow dent in the surface film rather than breaking through it.³
• Hydrofuge Properties: To prevent their bodies from becoming wet and sinking, these insects are covered in a fine, dense, water-repellent (hydrofuge) pile. This layer traps air, which helps keep the insect buoyant and prevents submersion.³

While they are supported by the surface film, they are not floating in the traditional sense; if they were to be pushed through the surface, they would sink.⁷³

What are the main differences between water treaders and water striders?

Water treaders and water striders are both semiaquatic bugs that belong to the order Heteroptera and utilize the water’s surface film for support, but they are classified into distinct families with different physical characteristics.⁹

Key Differences

• Taxonomic Classification: Water treaders belong to the family Mesoveliidae, while water striders belong to the family Gerridae.⁹
• Body Morphology: Water treaders are typically small, slender, and yellowish or greenish in colour. In contrast, water striders are often characterized by bodies that are widest at the middle or hind legs and taper toward the abdomen, creating the appearance of “broad shoulders”.⁹³
• Related Groups: It is important to distinguish these from smaller water striders (family Veliidae), which are generally stout-bodied and can be brown, black, or silvery. While all these groups share the ability to walk on water, their specific family classifications and physical builds help differentiate them in their respective aquatic habitats.³⁹

Both groups rely on their small, slender bodies and water-repellent (hydrofuge) hairs to remain on the surface without sinking.⁹

What other types of insects belong to the order Heteroptera?

The suborder Heteroptera, commonly known as “true bugs,” is a diverse group within the order Hemiptera. These insects are distinguished by their piercing-sucking mouthparts, the presence of scent glands in terrestrial and some aquatic species, and forewings that are typically divided into basal and apical halves of different textures.¹⁰¹¹

Below are several types of insects that belong to the suborder Heteroptera:

• Predatory and Specialized Bugs: Assassin bugs, ambush bugs, damsel bugs, and flower bugs.
• Aquatic and Semiaquatic Bugs: Water striders, water treaders, giant water bugs, backswimmers, water boatmen, creeping water bugs, and marsh treaders.
• Terrestrial and Plant-Feeding Bugs: Stink bugs, plant bugs, lace bugs, chinch bugs, and bedbugs.
• Other Notable Families: Shore bugs, stilt bugs, flat bugs, and toad bugs.¹⁰