Biology Reference
In-Depth Information
279
280
279
Water-lily beetle (
Galerucella nymphaeae
).
280
Larvae of water-lily beetle (
Galerucella nymphaeae
).
281
Galerucella nymphaeae
(Linnaeus) (
279-282
)
Water-lily beetle
An often important pest of water-lilies, including yellow
water-lily (
Nuphar lutea
) and, especially, white water-
lily (
Nymphaea alba
). Present throughout much of
Europe, including Britain and Ireland; an introduced
pest in North America.
DESCRIPTION
Adult:
6-8 mm long; dark brown to yellowish brown.
Egg:
0.75 mm across; sub-spherical, pale yellow to
yellowish orange, with a finely reticulated surface.
Larva:
up to 9 mm long; dark brown or black, but
yellow below.
Pupa:
5-7 mm long; black and shiny.
281
Pupae of water-lily beetle (
Galerucella nymphaeae
).
LIFE HISTORY
Adult beetles hibernate in the close vicinity of ponds
and pools, sheltering amongst vegetation and in dead
plant stems. They reappear in the following May or
June, to aggregate and feed on the leaves of water-lilies.
Eggs are deposited on the upper surface of the leaves in
groups of 12-18 and hatch in about a week. At first, the
larvae feed in groups, attacking the leaves and grazing
away the upper tissue; later, they feed singly and then
bite completely through the leaf blades. Flowers may
also be damaged. Pupation occurs on the upper surface
of the leaves, and young adults of the next generation
emerge in July and August. There are normally two
generations annually, but there may be three in heated
pools and in favourable southerly areas.
282
282
Water-lily beetle (
Galerucella nymphaeae
) damage to
leaves of
Nuphar
.
DAMAGE
Most significant damage is caused by the larvae,
attacked leaves becoming disfigured by irregular,
elongate holes and, if infestations are heavy, extensively
shredded.
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