Agelastica alni (Linnaeus, 1758)

Taxonomy: Polyphaga > Chrysomeloidea > Chrysomelidae > Agelastica > Agelastica alni

Common name: 

Alder Leaf Beetle


Agelastica alni
Agelastica alni
Agelastica alni
Agelastica alni
Agelastica alni


Size: 6-7mm
Basic colour: Deep metallic blue with a violet reflection.
Pattern colour: None
Number of spots: None
Other colour forms: Sometimes
Pronotoum: Deep metallic blue with a violet reflection.
Leg colour: Deep metallic blue with a violet reflection.

Has been considered in immigrant species, but this is not certain. Much life cycle information is from populations in France where new adults emerge in July and August, feed on alder leaves for 12-15 days, then enter a diapause on the ground surface, followed by hibernation until spring. Larvae usually feed on leaves of alders, but can develop on Downy Birch, Hazel and Goat Willow. Pupation occurs in an earth cell just below the ground surface, or in leaf litter. Adults can fly, but flight activity is low.


Status: Very rare in Britain. Previously classified as extinct, but specimens have been found recently and it is now considered 'Insufficiently Known' (RDB K) in the Red Data Book.
Habitat: Open, sunny areas in wetlands, especially alder carr. River banks. Wet woodland flushes.
Host plant: Alders, hazel, hybrid black-poplars, Goat Willow.
Overwintering: Adults overwinter in soil and leaf litter near host trees, emerging in April.
Food: Alder leaves.
Other notes: In southern France and Spain, adults may feed on fruits of the Rose family (e.g. pears, apples, plums, cherries).


Hubble, D. (2015). The distribution of Agelastica alni (Linnaeus) (Chrysomelidae) in Hampshire and its relevance to the species' British status. The Coleopterist 24(1): 53.
Formstone, B. (2014). Agelastica alni (Linnaeus) (Chrysomelidae) and Stenus contumax Assing (Staphylinidae) new to Wales. The Coleopterist 23(1): 36.
Ramsay, A.J. (2014). Agelastica alni (Linnaeus) (Chrysomelidae) in North Yorkshire. The Coleopterist 23(2): 65.
Lazenby, A.S. (2014). A population explosion of Agelastica alni (Linnaeus) (Chrysomelidae) in Sheffield, South Yorkhire and some records from surrounding areas. The Coleopterist 23(3): 142.
Ramsay, A.J. (2009). A new hostplant for Agelastica alni (Linnaeus) (Chrysomelidae) in Britain and observations of the species in Cheshire. The Coleopterist 18(2): 149.
Stenhouse, D. (2006). Records of Agelastica alni (Linnaeus) (Chrysomelidae) in South Lancashire and Cheshire in two successive years. The Coleopterist 15(1): 21.
Lewis, K.C. (2004). Early records of Agelastica alni Linnaeus (Chrysomelidae). The Coleopterist 13(3): 89.

Distribution (may take a minute to appear)