Water striders, often seen gliding across the surface of ponds and streams, are insects known for their ability to “walk on water.” These members of the Gerridae family, sometimes called pond skaters or water skeeters, inhabit various freshwater environments, from calm lakes to slow-moving rivers. Their slender bodies and long, specialized legs enable them to navigate the water’s surface with ease, making them a common sight in aquatic ecosystems.
Stages of Water Strider Development
The life cycle of a water strider involves incomplete metamorphosis, progressing through three distinct stages: egg, nymph, and adult. The egg stage begins when females deposit their eggs on submerged or emergent aquatic vegetation, rocks, or floating debris. These sticky eggs can be laid individually or in clusters, hatching after about 12 days.
Upon hatching, nymphs emerge, resembling wingless versions of adult water striders. These nymphs grow by undergoing several molts, shedding their exoskeleton. This developmental process takes about one month for nymphs to mature into adults. During their nymphal stages, they feed on various terrestrial and aquatic insects, similar to adults.
The final molt transforms the nymph into a sexually mature adult water strider. While most water striders are wingless, some species can develop wings, allowing them to disperse to new habitats if their current one dries up or becomes overcrowded.
Mating and Egg Laying
Reproductive activities for water striders commence in the spring. Male water striders often approach females and may tap their legs on the water’s surface, creating ripples that can attract predators. This behavior is thought to be a form of sexual coercion, pressuring the female into mating to stop the potential danger.
Once a male mounts a female, the female may use a genital shield to prevent forced insemination, allowing her to choose her mate. However, males have developed counter-behaviors, such as continuing to tap the water, to encourage the female to open her genital shield. Mating and egg-laying can continue throughout the adult female’s reproductive lifespan, which lasts one to three months. Females can lay eggs every one to two days, with daily fecundity ranging from 3 to 15 eggs per female.
Lifespan and Environmental Adaptations
Water striders have a lifespan of several months. In some regions, warmer climates allow for multiple generations within a single year. For instance, one generation might hatch in May to July and mature by late summer, while a subsequent generation hatching in August and September may live longer, up to eight months, surviving through winter.
As colder months approach, adult water striders seek shelter to overwinter. They find refuge in protected areas near water bodies, such as under leaves, logs, or rocks, or inside plant stems. They become active again in April, resuming their mating cycle. Their ability to survive on water is due to surface tension, where water molecules at the surface create a strong, elastic-like film. Their legs are covered in thousands of microscopic, water-repellent hairs called microsetae, which trap air and prevent them from sinking, allowing them to glide across the water’s surface.