This work is intended as a general and concise overview of Ephemeroptera biology, diversity, and services provided to humans and other parts of our global array of freshwater and terrestrial ecosystems. The Ephemeroptera, or mayflies, are a small but diverse order of amphinotic insects associated with liquid freshwater worldwide. They are nearly cosmopolitan, except for Antarctica and some very remote islands. The existence of the subimago stage is unique among extant insects. Though the winged stages do not have functional mouthparts or digestive systems, the larval, or nymphal, stages have a variety of feeding approaches—including, but not limited to, collector-gatherers, filterers, scrapers, and active predators—with each supported by a diversity of morphological and behavioral adaptations. Mayflies provide direct and indirect services to humans and other parts of both freshwater and terrestrial ecosystems. In terms of cultural services, they have provided inspiration to musicians, poets, and other writers, as well as being the namesakes of various water- and aircraft. They are commemorated by festivals worldwide. Mayflies are especially important to fishing. Mayflies contribute to the provisioning services of ecosystems in that they are utilized as food by human cultures worldwide (having one of the highest protein contents of any edible insect), as laboratory organisms, and as a potential source of antitumor molecules. They provide regulatory services through their cleaning of freshwater. They provide many essential supporting services for ecosystems such as bioturbation, bioirrigation, decomposition, nutrition for many kinds of non-human animals, nutrient cycling and spiraling in freshwaters, nutrient cycling between aquatic and terrestrial systems, habitat for other organisms, and serving as indicators of ecosystem health. About 20% of mayfly species worldwide might have a threatened conservation status due to influences from pollution, invasive alien species, habitat loss and degradation, and climate change. Even mitigation of negative influences has benefits and tradeoffs, as, in several cases, sustainable energy production negatively impacts mayflies.

This paper assesses the diversity of aquatic insects and insects with aquatic larvae used as human food. Over 250 species have been used as food in 48 countries around the world. Coleoptera comprises the largest number of species utilised, followed by Odonata and Hemiptera. All life stages are eaten but primarily larvae and adults. Currently, economic valuation is largely limited to Southeast Asia, although there is considerable potential to expand this. A few species includingLethocerus indicus (Lepeletier and Serville, 1825) have been negatively impacted due to exploitation as a food item coupled with other environmental pressures.

Freshwater ecosystems are particularly at risk from climate change due to the intrinsic link between the physical properties of the water environment and those species that live there. Mayflies, stoneflies and caddisflies are key indicators of the health of freshwater environments and their biological traits and ecological preferences determine their vulnerability to climate change. Traits and preferences for 289 British species were analysed, with voltinism, length of flight period, altitudinal preference and affinity to headwaters being the main factors causing vulnerability. Sixteen species were deemed to be at risk from climate change. These species are distributed across Great Britain, but particular hotspots of vulnerability are present in upland areas. These areas should be targeted with mitigation measures to reduce the impacts of climate change on populations of aquatic insects.

Evidence‐based conservation has made some major steps forward in the last two decades. However, the ‘landscape’ in which evidence is generated, funded and disseminated still has some elements that will need to be further developed if the UK's conservation sector is to achieve its collective nature recovery goals. This paper articulates a shared vision of the conservation evidence landscape in 2035. It was developed by representatives of 27 organisations involved in conservation and nature recovery across the UK. Solution: the authors identified a range of issues that will need to be addressed to allow the evidence base to support and guide nature recovery efforts. These will require action in four key areas: (1) evidence creation, (2) access to evidence, (3) evidence culture, and (4) enabling evidence‐based conservation.