Larvae of several families of small moths are the most common
foliage-mining pests in landscapes. Larvae of other insects,
mining flies, sawflies, and
wasps, also mine some plants, feeding inside leaves, needles,
shoots, or buds. Each kind feeds on only one or several closely
related plants. The host
species and characteristic form of the larva's damage help
to identify the insect species. Mature larvae of azalea
leafminer feed externally, webbing leaves together with silk.
Other groups of foliage miners
include cypress and arborvitae
foliage miners, casemakers
and skeletonizers, shield
bearers, and pine
tip or shoot moths.
Foliage-mining insects cause off-color patches, sinuous trails, or holes in leaves. Portions
of a leaf or patches of foliage may turn yellow or brown and die back. Larvae may be seen dropping from
foliage on silken threads. Severe infestations can slow plant growth; established woody plants tolerate
extensive foliage mining and are rarely if ever killed.
Provide proper care, especially irrigation, to keep plants vigorous. Prune out and dispose of foliage
infested with larvae to restore the plant's aesthetic appearance and provide some control. Plant resistant
species or varieties. If planting birch, plant least
susceptible species. Some foliage miners can be controlled
by natural enemies; conserve beneficials by avoiding broad-spectrum persistent insecticides..
Trails caused by the madrone leaf miner
Shield bearer damage