Using Weather Radar to Track an Enemy of our Forests – The Spruce Budworm - July 21, 2015

Posted on July 21 2015

There is considerable research ongoing outside of Atlantic Canada to better understand the spread of spruce budworm outbreaks. Here is a great example of some of that work, as described by my colleague and team leader of this project, Dr. Yan Boulanger of the Laurentian Forestry Centre in Quebec City. – Rob Johns

During the night of July 15 2013, an astonishing number of spruce budworm moths were observed in Rimouski, Quebec. They were so numerous that people were literally “shovelling” moths the next morning in order to clean their driveways and balconies. Following this event, scientists asked: Where did these moths come from? Are they local? Are they coming from elsewhere, and if so, from how far away? We wanted to know more about how spruce budworm populations spread or disperse. We think that dispersal may be an important process to synchronize populations over very large areas and increase the scale of outbreaks. But how can we quantify moth dispersal? For example, tagging and tracking individual moths would be an impossible task. Some indirect methods exist (e.g., eggs to moth ratio, DNA, phenological models, etc.) but these techniques make it very difficult to actually infer where moths are coming from.

Scientists have many tricks up their sleeves when it comes to getting the information they need - and here’s one of them: if these bugs were so numerous that night, could we actually “see” them on radar? A picture really is worth a thousand words - just have a look at this video. What you see are echoes from weather radar for Val d’Irene (near Amqui, Québec) taken during the night of July 15 2013. Usually, this type of radar is used to track precipitation (snow, rain). At this time, there were no clouds in the sky over most of the area. However, you can see a huge “shower” crossing the river during the evening. This “cloud” is actually millions, or more likely billions of moths drifting over St. Lawrence, from the Côte Nord towards the Bas-Saint-Laurent region.  Some of these individuals seem to drift as far as northern New Brunswick! Stunning isn’t it?

In collaboration with radar specialists from the J.S. Marshall Observatory and McGill University, scientists from NRCan will use weather radar data to study spruce budworm moth migration. This research will help develop a tool to better track moths and increase our understanding of how moths migrate during an outbreak. This tool will complement others being developed as a part of this research program, including pheromone and light traps and the citizen science project.  

Project Manager : Yan Boulanger, Laurentian Forestry Centre

Back to Archive