Infestation in the field is usually low. However, sporadic heavy outbreaks may
occur, particularly during or after a prolonged dry period.
Widespread in Asia, Papua New Guinea, Australia and Africa.
The larvae are small caterpillars which feed on the green tissue inside the
leaf, leaving the transparent upper and lower membranes (epidermis) intact.The young larvae
enter the leaf and form serpentine mines (narrow, grey-brown or silvery tracks). As the
larva matures, it consumes a broader patch of the leaf, forming blotch mines. Later holes are produced as the mined tissues are
destroyed. The lower surface of the infested leaves become dirty with small
grains of blackish frass and show silken webbings
containing the small pupae. During high
infestation, the leaves become brown. A serious outbreak can cut down the
effective leaf surface for plant food production resulting in reduced storage
Egg. The eggs are oval, flattened against the leaf surface;
translucent, greenish white with granulate surface which turns yellowish when
about to hatch.
Larva. The emerging larvae are
distinctly segmented with a rather pointed heads and abdomens. A mature larva
measures 5.5 mm long. The larva has a yellowish body with paired pink spots on
the dorsolateral sides of the thorax which later disappear and are replaced by
red tubercles in all segments.
Pupa. The pupae measuring 3.5 mm
appear green at first with mottled red markings. Later the red markings
disappear and they turn dark brown with lateral projections on the abdomen.
Adult. The adults are very small moths, 3.5 - 4.0 mm long with grayish
to brown bodies and light brown scales.
The eggs are laid singly or in groups usually on the lower
surface of the leaf near the midrib, veins or at the base of the leaf blade.
Incubation lasts 5-6 days. The insect undergoes five larval instars. During the
fifth instar, the larva undergoes a short pre-pupal period, comes out of the
mine and produces numerous silken threads which fix and support the pupa on the
lower surface of the leaf. Pupation lasts 3-6 days. A female adult is capable of
laying 1-67 eggs during the 1-2-day oviposition period.
Apart from sweetpotato, leaf miners can also survive on Ipomoea
triloba, I. aquatica and I. purpurea.
Leaf miners are generally controlled by predators and parasites
like Apanteles sp.
A number of insecticides provide effective control of leaf miners. Consult your local supplier or extension service for current recommendations.
Amalin, D.M. and Vasquez, E.A. 1993. A handbook on Philippine
sweet potato pests and their natural enemies. International Potato Center (CIP),
Los Baņos, Philippines. 82 p.
Gapasin, D.P. 1981. Biological studies of sweet potato insect
pests and their natural enemies. Terminal Report. A research study funded by the
Philippine Council for Agriculture and Resources Research (PCARR). Department of
Plant Protection, Visayas State College of Agriculture. 210 p.
E.A. and C.E. Sajise. 1990. Pests of sweet potato: Insects, mites and diseases.
Philippine Root Crop Information Service, Philippine Root Crop Research &
Training Center. 65 p.
Contributed by: Erlinda