The Bagworm Moth (Thyridopteryx ephemeraeformis) is an important pest on variety of trees and shrubs in many regions. Overwintered eggs in hanging bags typically emerge as larvae in spring and begin to feed. There is one generation per year. Researchers have developed a model, and available on the Pest Prophet app,  to predict adult emergence for each generations, based on temperature data.

Initiating the Biofix

To properly use the model, the biofix must first be set. This is the date that will serve as the starting point for growing degree day accumulation. For this type of model the biofix date should be set to March 1st for the Northern Hemisphere.

Growing Degree Day Accumulation and Treatment

After the biofix is set, growing degree day accumulation can begin, using a lower threshold of 50F. Calculating growing degree days can be done using daily high and low temperatures, or using hourly temperature data using the Pest Prophet app. Larvae emergence occurs between 600-900 GDD(F). These larvae can be targeted for treatment by insecticides.

Source:

Growing Degree Day Information. Nathan W. Siegert, Deborah G. McCullough and Jeffrey A. Andresen. Michigan State University, 2 October 2015. Web. 25 February 2016.

Using Growing Degree-Days for Insect Pest Management. Thomas Kowalsick and Scott Clark. Cornell Cooperative Extension in Suffolk County, March 2012. Web. 25 February 2016.