The blue willow beetle (''Phratora vulgatissima''), formerly ''Phyllodecta vulgatissima'', is a herbivourous beetle of the family
Chrysomelidae
The insects of the beetle family Chrysomelidae are commonly known as leaf beetles, and include over 37,000 (and probably at least 50,000) species in more than 2,500 genera, making up one of the largest and most commonly encountered of all beetle ...
. It is dark with a metallic sheen that ranges from a blue color to bronze. It is distinguished from ''P. vitellinae'' by the latter more commonly displaying bronze coloration. European ''Phratora'' species can be distinguished based on morphology of female genitalia.
The larvae undergo three instar stages from hatching to pupation. This beetle is found throughout Europe and Scandinavia, and occurs in China.
Ecology
The blue willow beetle is found on willow (''Salix'') species, whose leaves contain low levels of salicylates in fens, carrs and on river banks, but also often in willow
short rotation coppice
Short rotation coppice (SRC) is coppice grown as an energy crop. This woody solid biomass can be used in applications such as district heating, electric power generating stations, alone or in combination with other fuels. Currently, the leading ...
and other agricultural landscapes. It often aggregates on host plants. On '' Salix cinerea'', it prefers and is more common on female than male trees despite higher egg predation exerted by the common flowerbug ''
Anthocoris nemorum
The common flowerbug (''Anthocoris nemorum'') is a common minute pirate or flower bug.
Distribution
The common flowerbug is found across Europe and the Palearctic to China. It is common in Great Britain and Ireland. In the Alps it is found t ...
'' on female trees. It is univoltine in Sweden but can produce multiple generations per year in other parts of its distribution range. Proliferation of
larvae
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
The ...
and
egg
An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the a ...
lichen
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.tree bark. Predators of blue willow beetle eggs include ''A. nemorum'' and ''
Orthotylus marginalis
''Orthotylus marginalis'' is a species of stinkbugs from Miridae family that can be found throughout Europe (except for Liechtenstein and various European islands). then east across the Palearctic to Central Asia and Siberia.
Description
Adult ...
Perilitus brevicollis
''Perilitus brevicollis'' is a species of parasitoid wasp in the family Braconidae. The host of this wasp is the blue willow beetle
The blue willow beetle (''Phratora vulgatissima''), formerly ''Phyllodecta vulgatissima'', is a herbivourous b ...
'' and consumed by ''R. punctatus''.
The blue willow leaf beetle as a pest
In Europe, the blue willow beetle can become a severe herbivore pest on willows. For plantations of common osier (''Salix viminalis''), herbivory reducing biomass production by up to 40% has been estimated . It is susceptible to '' Bacillus thuringiensis tenebrionis'' and also Spinosad when treatment is applied to affected plants.