Alder flea weevil

The Alder flea weevil (Latin: Rhynchaenus testaceus) is a small beetle belonging to the Curculionidae family. Although these insects are small in size, they are recognized as significant pests that can impact the health and visual quality of various deciduous trees, particularly in forestry and urban environments.

This pest primarily feeds on tree species such as linden, birch, and alder. The adult beetles cause damage by feeding on foliage, while the larvae are internal feeders, creating mines within the leaf tissue, which can lead to widespread infestation across individual trees and nearby stands.

The biological cycle of the beetle is synchronized with the vegetative season of its host plants. Overwintering occurs in leaf litter or under the bark of trees. As temperatures rise in spring, the adults emerge to feed and lay eggs. The larvae develop inside the leaf, protected from many external predators and adverse weather conditions.

The damage caused by Rhynchaenus testaceus is identified by the presence of small holes made by adults and distinct, winding tunnels known as mines made by the larvae. Heavy infestation leads to leaf browning, early senescence, and premature leaf drop, which can stress the tree if it occurs repeatedly over several years.

Control measures for this weevil focus on integrated pest management practices. Key strategies include:

• Applying systemic insecticides when adult activity peaks.
• Removing and destroying leaf litter in the autumn to eliminate overwintering sites.
• Monitoring trees in late spring to detect early signs of larval mining.