The alder leaf beetle with the scientific name Agelastica alni is a small but very noticeable beetle due to its characteristic color, which hikers most often encounter near water. Its oval and strongly convex body is metallically shiny, with color shades ranging from dark blue to violet. It is easiest to recognize by its noticeably narrower pronotum compared to the wide elytra, giving it a characteristic squat shape.
As its name suggests, this beetle is closely associated with alders. Adult specimens and their larvae feed on the leaves of these trees, so they can be observed in greater numbers from spring to late summer, sunning themselves on riparian shrubs. Although small, they are a real decoration of riparian vegetation in our hills due to their color, which creates wonderful reflections in sunlight.
In nature, they are an important part of the food chain, as many birds or other insectivorous animals feed on them. When you next notice them by a stream, know that these metallic blue beetles are a clear sign that you are near a healthy riparian ecosystem. Encountering them is an excellent opportunity for macro photography, as despite their small size, they are an extremely rewarding subject for any nature lover.
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