Pest description and crop damage This adult is a very small fly less than 0.1 inch in length. The larvae are very small, legless and orange in color when young, aging to white in color. The feeding of the larvae on leaves causes them to curl up along the midrib. Curled leaves have reddish-gall-like swellings and later on in the season turn black and fall off. Extensive feeding activity can stunt young trees, however in mature trees this is less of a pest. Pear leaf midge is seldom a problem in commercial pear orchards that receive a regular spray program. However, it can be a problem occasionally in the Willamette Valley and Hood River districts of Oregon.
Biology and life history The midge overwinters as a pupa in the soil. Around bloom the adults emerge and lay eggs in the leaves just as they are unfolding. The hatched larvae feed within the curled leaves, often numbering up to 30 larvae per leaf. When mature, the larvae chew an exit hole and drop to the ground to pupate. There may be several generations per year, the number depending entirely on the availability of new growth, as the adults lay eggs only on new foliage.
Pest monitoring Adults can be monitored with yellow sticky traps. Presence of the midge is also easily confirmed by the presence of the characteristic damage.
Management-chemical control: HOME USE
- acetamiprid-Toxic to bees.
- azadirachtin (neem oil)-Products containing neem extract may be phytotoxic to some pear cultivars. Some formulations are OMRI-listed for organic use.
- bifenthrin-Highly toxic to bees.
- gamma-cyhalothrin-Highly toxic to bees.
- lambda-cyhalothrin-Highly toxic to bees.
- permethrin-Highly toxic to bees.
- pyrethrins-Highly toxic to bees. Some formulations are OMRI-listed for organic use.
- zeta-cypermethrin-Highly toxic to bees.
Management-chemical control: COMMERCIAL USE
Petal fall is the optimal treatment timing if chemical control is required.
- spirotetramat (Ultor) at 10 to 14 oz/A. REI 24 hr. PHI 7 days. Minimum 14 days between applications. Must be used with an adjuvant; see label. The product label lists pear leaf midge under pests suppressed. Do not apply prior to petal fall.