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INSECT AND MITE PESTS


Spotted Tentiform Leafminer

STLM were probably introduced to the U.S. from Europe in the 1800's. Their hosts include apple, hawthorn, wild cherry, quince, plum and crab apple. They are relatively new pests to Kentucky, and as such their appearance is sporadic.

Eggs are small, elliptical, flattened and laid singly on the undersides of leaves. Eggs are nearly transparent early on but soon turn creamy to yellow. Small larvae are extremely flat, legless and live in the small space between leaf surfaces. Larger worms (less than 1/4") more closely resemble caterpillars, having visible legs and head capsule. Pupae are elongated and cylindrical. A very close look will disclose the presence of wings, eyes, antennae, etc. Adults are small moths (1/8 in.) and golden brown with white spots or bands.


Leaf Miner Damage


TLM overwinter as moths in leaf litter. Egg laying occurs in late March to early April. Egg hatch will occur 2 to 3 weeks later. Small larvae will begin to appear around bloom. These larvae will feed in a "U" shape pattern which delineates the area that will be the mine. This is normally only visible from the underside of the leaf. Larger, tissue feeding larva will feed on both the upper and lower leaf surfaces.

After about a month of feeding, larva will pupate within the mine and moths will begin to appear in about another month. There may be as many as four generations per year.

SCOUT: Examine 100 leaves per tree and count the number of mines.

RECORD: The number of mines per 100 leaves.

ACTION THRESHOLD: Thresholds vary during the season, see Appendix 3. Typically, 100 mines per 100 leaves until May 15, 200 mines per 100 leaves from May 15 to July 1, and 300 mines per 100 leaves after July 1.



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