Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 12

Chapter 2
Insects

Order COLLEMBOLA (springtails)

Family SMINTHURIDAE Family ONYCHIURIDAE

Globular-bodied springtails with thorax and abdomen
fused; antennae long; ocelli usually present.

Springtails without ocelli, but with complex sensory
organs on the antennae and with mandibulate
mouthparts.

Bourletiella hortensis (Fitch)
syn. B. signatus (Nicolet)
Garden springtail
An often common pest, particularly in wet, acid soils.
Damage is caused to seedling plants, including various
ornamentals; conifer seedlings in forest nurseries,
especially beach pine ( Pinus contorta ), are seriously
affected. Widely distributed in Europe; also present in
North America.

Onychiurus spp.
White blind springtails
Various species of Onychiurus (e.g. O. nemoratus and
O. stachianus ) cause damage to seedlings, pitting the
cotyledons, hypocotyl and roots, and chewing the root
hairs and rootlets; attacked seedlings collapse and die,
often keeling over at about soil level. On older plants,
leaves in contact with the soil may also be holed and
skeletonized. Damage occurs on various outdoor and
greenhouse plants, including ornamentals. The
springtails are abundant in wet soil with a high organic
content, and often gain entry to pots and seed boxes if
these are placed directly onto infested ground. The pests
may also be introduced into containers if unsterilized
compost is used. Individuals (up to 3 mm long) are
white and stout bodied, with a large head, short
antennae and legs, and six abdominal segments; the
springing organ is reduced or absent. They breed
continuously in favourable conditions. Development
from egg to adult takes several months, and the insects
undergo several moults even after the adult stage is
reached.

DESCRIPTION
Adult: 1.5 mm long; black to dark green, often spotted
with white; head large, with long antennae and
prominent, black, yellowish-bordered eyes; abdomen
globular, with a small ventral tube-like sucker and a
forked springing organ.

LIFE HISTORY
Eggs are laid in the soil, usually in small groups, each
female depositing up to 100 in about three weeks. The
eggs swell rapidly after laying and hatch shortly
afterwards. Under favourable conditions maturity is
reached in 2-3 months but development can take much
longer, individuals continuing to moult even after the
adult stage is attained. Breeding is continuous
throughout the year but reaches a peak in the spring, the
insects being most numerous from late April to the end
of June.

DAMAGE
General: the hypocotyl and cotyledons of seedlings are
pitted, and holes are formed in the young leaves, but
damage rarely occurs after July. Conifer seedlings:
damage to the hypocotyl and cotyledons results in
stunted seedlings with a brush-like mass of swollen,
distorted needles; such seedlings develop into useless,
multi-stemmed plants.