PENNSYLVANIA—November is National Aviation History Month, when we celebrate America’s contributions to past and future endeavors in aviation. For the USDA Forest Service’s Eastern Region, aviation continues to be a valuable tool for protecting forest health, especially to fight the widespread defoliation caused by spongy moth outbreaks across the region. 

The connection between aviation and forest health was at the heart of a training workshop held earlier this fall in Gettysburg, Penn., for state partners on aerial pesticide application. Hosted by the Forest Service’s Forest Health Protection program and the Aerial Application Safety Council, the workshop’s goal was to increase practitioners’ knowledge of spray aircraft and application methods used for spongy moth treatments. 

More than 35 people from 13 states attended the three-day workshop, helping to meet a pressing need regionwide. With many retirements and staff changes in federal and state cooperator spongy moth management programs, proactive efforts like this workshop are critical to maintaining and growing this skill set. 

Since being introduced in the U.S. in 1869, spongy moths have become a forest pest causing defoliation outbreaks across eastern states. Populations have spread into the Midwest and South. In the short term, a tree can withstand defoliation and typically re-foliates after the spongy moth caterpillar has pupated into the moth. However, excessive defoliation over multiple years can leave the tree stressed and more susceptible to other pests and diseases, causing the tree to die.

While aviation resources can assist with a wide range of forest health monitoring efforts and pesticide applications, spongy moth is the main target of aerial pesticide application across the eastern states. These pesticides are effective against the spongy moth but pose a low risk to humans and other non-target species.

The trend of extensive defoliation from spongy moth continued in many eastern states this year, as populations have been high for the last few years. More than 500,000 acres were treated for spongy moth in 2024 using aerial applications. Additional treatment work is expected in 2025.

This year’s training workshop in Gettysburg included sessions on aerial application; aviation safety and briefings< project planning and organization, and pesticides. Hands-on modules were held at the Gettysburg airport with spray helicopters and spray equipment. Training topics included aircraft systems, design and construction, spray nozzles, helicopter and spray system inspections, spray and flight following software, and aircraft tracking. Additional hands-on sections covered establishing the pesticide flow rate and the number and size of spray droplets released from spray aircraft and equipment.  

The workshop focused specifically on aerial application using helicopters, which have advantages over fixed-wing airplanes in certain situations. The choice between fixed-wing aircraft and helicopter depends on factors that vary case by case. “Helicopters are typically used more frequently in mountainous areas and in treatment locations where the distance to a landing strip for a fixed-wing aircraft is prohibitive,” said John Kyhl, pesticide use coordinator for the Forest Service’s Eastern Region. 

This year’s training workshop was sponsored by the National Lymantria Management Board and the USDA Forest Service.