The Alder, Alnus glutinosa, is a common tree alongside water. It can be recognised by its oval, slightly heart-shaped, leaves that taper into the stalk, and by its small cones. Like most native plants, it supports a wide range of other wildlife that rely on it for part of their lifecycle. So if you have recognised a Common Alder tree, look for the associated species featured below. Visit the Common Alder page on NatureSpot.
Alder Leaf Beetle
Agelastica alni is a distinctive, dark metallic blue coloured species measuring around 7mm in length. It feeds mainly on Alder but is occasionally found on other deciduous trees such as Beech, Hazel and Hornbeam. The black larvae can be found in July and August when they can cause significant leaf damage.
Gall - Eriophyes laevis
The mite Eriophyes laevis causes galls to form on the leaves of Alder (Alnus glutinosa). The galls start off shiny yellow, becoming green then red, purplish or brown. They are scattered over the leaf, often numerous, and with a small opening below. The gall is seen more often than the mite.
Gall - Acalitus brevitarsus
Acalitus brevitarsus is a mite that causes blister like galls to form on the leaves of Alder. Like many mite galls, the leaf is made to grow clusters of hairs, called erineum, among which the mites live. On the underside of the leaf these galls have a shiny pale brown appearance. The galls are seen more often than the mite.
Leafmine - Agromyza alnivora
The larvae of this fly mine the leaves of various species of Alder creating an upper surface gallery, narrow at first but widening considerably towards the end. Frass is typically in two rows.
