Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 131

Galerucella luteola (Müller) ( 276-278 )
syn. Pyrrhalta luteola (Müller); Xanthogaleruca
luteola (Müller)
Elm leaf beetle
An often important and destructive pest of elm ( Ulmus ).
Also associated with Caucasian elm ( Zelkova
carpinofolia ) and horse chestnut ( Aesculus
hippocastanum ). Widely distributed in mainland
Europe, Asia Minor and North Africa, but absent from
the British Isles; an introduced pest in North America.

LIFE HISTORY
Beetles emerge from hibernation in April and May.
They then fly to host plants and begin feeding on the
leaves, forming irregular holes between the major veins.
Eggs are laid in groups of 10-30 from May onwards,
typically in 2-3 rows close to a secondary vein on the
underside of a young leaf. Each female is capable of
depositing several hundred eggs, and some may
successfully lay over a thousand. Eggs hatch in about
ten days. The young larvae feed gregariously on the
underside of the leaves from May onwards. At the early
stages of development larvae are unable to feed on the
toughened, older foliage. However, later, when they
also become less gregarious, they attack leaves of
various ages. Larvae are fully fed in about three weeks.
They then pupate amongst leaf litter or in the soil, new
adults emerging from early July onwards. Larvae of a
second brood complete their development later in the
summer. They eventually develop into adults which
usually feed briefly before overwintering.

DESCRIPTION
Adult: 5-7 mm long; yellowish brown to olive-brown,
marked with black on head, thorax and elytra. Egg:
1.0 0.5 mm; lemon-shaped; pale yellow to brownish

white. Larva: up to 10 mm long; head black, body
yellowish to blackish, marked with numerous black
verrucae and plates. Pupa: 5-7 mm long; yellowish
orange.

×

DAMAGE
Adults and larvae cause considerable disfigurement of
the foliage, and leaves may be completely destroyed.
Heavy infestations affect the growth and vigour of host
plants.

276

276 Elm leaf beetle ( Galerucella luteola ).

277 278

277 Larva of elm leaf beetle ( Galerucella luteola ). 278 Hatched eggs of elm leaf beetle ( Galerucella luteola ).