The Alder Leaf Beetle is a small, metallic blue insect, which can be seen in open, sunny areas in wetlands, typically alder carr. Throughout this time, they will feed mainly on Alder leaves but they're known to eat Beech, Hazel and Hornbeam, too.
They're not severe pests, with plants tolerating most damage. Typical symptoms include holes in the leaves, which is purely aesthetic. Young trees may be more vulnerable to stunted growth, so picking off insects by hand (where appropriate) is advised at first.
Adults are active from April to August. Larvae can be found on trees during May and July. This beetle was once thought to be extinct from the UK, being absent for almost 70 years. They have now repopulated some parts of the UK and are showing signs of steady recovery.