How to Manage Pests
UC Pest Management Guidelines
Scientific name: Liriomyza
sativae and Liriomyza trifolii
(Reviewed 8/07, updated 12/08)
In this Guideline:
Leafminer adults are very small flies, 0.1 inch (2.5 mm) long, black to blue, with parts of the
thorax, legs, and abdomen yellow. Usually there is a prominent yellow area at
the base of the wings. The minute white eggs are laid just under the leaf
epidermis and hatch in 4 to 6 days. Maggots are normally concealed between leaf surfaces in the mines where they feed; they
range from yellow to white, are 0.25 to 0.33 inch long, blunt at the rear end,
and pointed in front. Pupation occurs in the mines or in the ground. During summer, the life cycle requires
about 23 days. There are from three to five generations a year.
Leafminers are occasionally a problem in beans generally during the
latter part of the production season. The maggots feed between the upper and
lower leaf surfaces causing large whitish blotches, or in the case of
serpentine leafminers, slender, white, winding trails through the interior of
Because of numerous common parasites,
leafminers are generally not serious pests, but can be sporadic in their
damage. The destruction of beneficial insects by frequent applications of
insecticides applied to control other pests can result in leafminer outbreaks.
Of the numerous parasites that attack leafminers in California, the most
abundant is the parasitic eulophid wasp, Solenotus intermedius, but Diglyphus spp. and Chrysocharis spp. are probably the most important for controlling
Biological control and sprays of the
Entrust formulation of spinosad are organically acceptable.
and Treatment Decisions
To check for leafminers, evaluate the amount of mining in the leaves during
weekly observations for other insect pests beginning at crop emergence. Continue to monitor leaves during vegetative
growth, flower bud to bloom, and pod fill periods. Economic thresholds have not been determined on all bean varieties. On
pinks and kidneys, treat if 25% of the surface of older leaves is mined and
mines are present in the new leaves.
|When choosing a pesticide, consider information relating
to the impact
on natural enemies and honey bees
and environmental impact. Not all registered pesticides are listed. Always read label of product being used.
||MODE OF ACTION GROUP NUMBER1: 5
||COMMENTS: Do not apply more than 12 oz/acre/season of Success
or 3.75 oz/acre/season of Entrust. For blackeyes, be sure to apply with an oil.
||MODE OF ACTION GROUP NUMBER1: 17
||COMMENTS: Not for use on cowpeas.
UC IPM Pest Management Guidelines:
UC ANR Publication
Insects and Mites
L. D. Godfrey, Entomology, UC Davis
R. F. Long, UC Cooperative Extension, Yolo County
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