Biology Reference
In-Depth Information
264
265
264
Rosemary beetle (
Chrysolina americana
).
265
Larva of rosemary beetle (
Chrysolina americana
).
266
266
Adult of
Chrysolina polita
.
Chrysolina americana
(Linnaeus) (
264-265
)
Rosemary beetle
In recent years, this southern European beetle has
become firmly established in Britain on ornamental
lavender (
Lavendula
) and rosemary (
Rosmarinus
officinalis
) bushes in private gardens and elsewhere.
The beetles aestivate on host plants during the summer,
and become active from late August onwards. They then
mate and lay eggs, with egg laying continuing
throughout the winter months. Eggs hatch in about two
weeks. The mainly grey, sac-like larvae (each up to 8
mm long) then browse on the leaves before eventually
entering the soil to pupate. New adults appear two or
more weeks later, depending on temperature, there
being just one generation annually. The rather bulbous
adults (
c
. 8 mm long) are metallic green, with
longitudinal purple stripes on the thorax and elytra. The
pest also breeds on other Lamiaceae, including sage
(
Salvia
) and thyme (
Thymus
).
Chrysolina polita
(Linnaeus) (
266
)
Although mainly an inhabitant of damp meadows,
adults of this generally common species occur
occasionally on lime (
Tilia
) and ornamental willow
(
Salix
), causing minor damage to the leaves. Individuals
are 6.5-8.5 mm long, broad and convex, with a golden-
green, sometimes reddish-flushed head and thorax, and
dull-metallic, brownish-red, irregularly punctured elytra
(cf.
Chrysomela populi
, p. 136).
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