European Rose Slug
Contact: Eric Day, Manager, Insect Identification Laboratory
August 1996
European Rose Slug
Hymenoptera: Tenthredinidae, Caliroa aethiops
Plants Attacked
Most varieties of rose.
Description of Damage
The larvae feeds on the upper surface
only, skeletonizing the leaves, only the soft tissue is eaten,
leaving the veins and lower epidermal tissues.
Identification
The larva is yellowish green in color and
partially translucent with ingested food causing the digestive
track to appear to be dark olive green. There are two other
species of sawfly on rose, the bristly rose slug and the coiled
roseworm, both of which do not skeletonize, but chew holes in the
foliage.
Life History
Eggs are laid in pockets in the leaf tissue near
the edge of the leaflets. The larvae skeletonize the upper
surface of the leaf. When they are full-grown, the larvae leaves
the bush and enters the ground where it constructs a cell,
cementing together particles of sand and earth to form a
capsule-shaped chamber. This stage of quiescence occupies the
largest part of the year. One generation per year.
Overwintering stage - pupa.
Control
Application of insecticide when the initial signs of
skeletonizing appear is effective. Emergence of adults occurs in
late spring, but may occur over a period of time. Surveillance
of plants is important to determine when plants should be treated
and when treatments need to be repeated. Feeding progresses
rapidly. A period of relatively few days results in extensive
skeletonizing, if infestations are overlooked and not treated.
Remarks
Rose slugs are more unsightly and aesthetically
undesirable than seriously damaging to the plants. They are
conspicuous and cause concern resulting in numerous calls for
diagnosis. The application of control measure is a judgment
decision based on the immediate aesthetic value of the foliage.