The Lacanobia Fruitworm a pest of Apples and a large variety of row crops, shrubs, trees and weeds. The larvae feed on the foliage early in the season and then on fruit later in the season.

Lacanobia Fruitworm Life Cycle Stages

Lacanobia Fruitworm overwinter as pupae in the soil, and adults emerge in late spring or early summer. The first generation larvae emerge in early summer and usually feed primarily on foliage, thought they can sometimes feed on early fruit. Defoliation may occur in cases of extreme infestation.

Second generation adults emerge in late July, and these adults remain active until fall. The next generation of larvae feeding usually begins in late summer and continues into fall. This generation feeds more on fruit and can cause major crop damage in apples.Researchers at Washington State University have developed a growing degree day model to help track the life cycle stages of the Lacanobia fruitworm to assist in pest management decisions such as trap placement and insecticide sprays.

Calculating Growing Degree Day Units

The Lacanobia Fruitworm Growing Degree Day model uses a lower threshold of 44F and an upper threshold of 90F. It can be calculated with daily high and low temperatures, using the sine model to estimate growing degree day units, or the Pest Prophet app can be used to calculate GDD accumulation from hourly temperature data for a specific field.

Using Mar. 1st as a default “biofix” date, or starting point for accumulation. The first adult emergence occurs at approximately 390 GDD (F). This can be used an approximate target for beginning to place traps in the orchard. First generation egg hatch occurs at approximately 770 GDD (F) after Mar 1.

To improve accuracy, the biofix date should be re-adjusted when adult Lacanobia Fruitworm moths are first consistently caught in traps. The first larvae will emerge approximately 380 GDD (F) after this biofix date. This can easily be done in the Pest Prophet app.

Source:

Doerr, Michael D., Brunner, Jay F., and Jones, Vincent P. 2002. Temperature-Dependent Development of Lacanobia subjuncta (Lepidoptera: Noctuidae). Environ. Entomol. 31(6): 995-999