Corn Earworms and Lygus Bugs Infesting Strawberries

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The corn earworm (Helicoverpa zea, Lepidoptera: Noctuidae), a significant pest known for its broad host range, has been reported infesting various strawberry fields in North Carolina and Virginia this week. This pest, typically found in corn and tomatoes, can cause extensive damage to strawberries, affecting the fruit quality and yield.

Because the earworms feed directly on the fruit, contact insecticides are not likely to control them. Systemic insecticides that move through the plant tissue, such as Coragen (chlorantraniliprole), or insecticide products with translaminar activity that move inside the leaf tissue where they are applied, such as Harvanta (cyclaniliprole),are the best option to remediate these outbreaks. Two insecticide applications scheduled one week apart are enough to mitigate infestation. Some formulations of Bt-based insecticides are approved to control corn earworms in organically-grown strawberries.

An opened strawberry fruit hold by a person showing a grown corn earworm larva inside

Grown corn earworm larva inside a strawberry

An opened strawberry fruit hold by a person showing a young corn earworm larva inside

Corn earworm young larva feeding on strawberry

The Tarnished plant bug also  also known as Lygus bug (Lygus lineolaris, Hemiptera: Lygaeidae, is the eastern US species) has also been reported in various strawberry farms in North Carolina. This pest usually infest strawberries during the last weeks of harvest in early June. However, moderate to severe infestations have been observed 2-3 weeks early this year.

Feeding by nymphs and adults results in distorted, “cat-faced” strawberries due to seed feeding. Lygus bugs start feeding on small growing fruit that limits its normal growth causing deformed (“cat-faced”) unmarketable fruit. These insects can be easily seen with the naked eye resting on the plants during the day.

Because Lygus bugs are highly mobile, systemic products are the best option to remediate early outbreaks, such as Transform (sulfoxaflor) or Assail (acetamiprid). These products are highly toxic to bees; thus, read the label closely to keep your pollinators safe and apply them as late as possible in the day to avoid overlaps with the bees’ activity peak.

A yellow snapdragon flower with a Lygus insect resting inside one of its petals

Lygus bug in snapdragon flowers

A hand holding a strawberry still attached to the plant. The strawberry is malformed due to Lygus bug feeding

Cat-faced strawberry fruit

Two strawberries still attached to the plant showing malformations due to Lygus bug feeding

Damaging population outbreaks of corn earworms and Lygus bugs in strawberries are most likely to occur during periods of warmer than usual temperatures. Historical temperature data for NC indicate that maximum temperatures in May fluctuate close to 80°F. However, we reached more than 90°F during the 1st week of May, which may have contributed to the establishment of these pests.

Refer to the North Carolina Agricultural Chemicals Manual for materials recommended for use against corn earworms and Lygus bugs in North Carolina and the Southern Region Small Fruit Consortium Strawberry IPM Guide for regional recommendations.