Marin Rose Society

FAST FACTS - Fruittree Leafrollers
by Nanette Londeree, Master Rosarian

SIGNS

Flat egg masses on small stems or branches

A green larva (or caterpillar) ľ to one inch long with a black head (when young), turning to brown that wriggle vigorously when disturbed and drop to the ground on a silken thread, March through mid-May

A pupa just under 1/2 inch long, light to dark brown, and is usually formed within the rolled leaf; silk webbing lines the area around the pupa

Leafroller Adult SYMPTOMS

Tender new leaves with a ragged appearance

Leaves that are rolled and tied together with silken threads

Defoliated grass or other plants beneath the plant

CAUSE

Leafroller Damage

Larvae of the fruit-tree leafroller, Archips argyrospila or A. rosanus

OPTIMAL CONDITIONS

Fruit or shade trees in the area

March through May when larvae hatch

Abundant tender new leaves and bud

TREATMENT

Prevention:

Maintain good garden sanitation

Encourage beneficial insects and birds including certain tachinid flies and ichneumonid wasps (main parasites), lacewing and certain beetles, insect eating birds (common predators)

Elimination:

Inspect new foliage and look for feeding injury and the small larvae (caterpillars); trim off and destroy

Spray with Bacillus thuringiensis; thorough spray coverage is required for control and it’s only effective on fruittree leafroller larvae when they are small (less than 1/2 inch long); it usually requires more than one application

Apply sprays only when there is evidence of a damaging leafroller population, such as large numbers of larvae early in the spring or large numbers of egg masses

GOOD GUY / BAD GUY?

A bad guy that can make a mess of your roses, though doesn’t do significant lasting damage

Photos courtesy of Baldo Villegas; from top: fruittree larvae, adult, damage to rose and nest.

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FAST FACTS - Fruittree Leafrollers by Nanette Londeree, Master Rosarian

FAST FACTS - Fruittree Leafrollers
by Nanette Londeree, Master Rosarian