Spotlight: Citizen scientists and the eastern spruce budworm outbreak

Scientists are calling on citizens to help track a major insect outbreak in eastern Canada’s fir and spruce forests.

Eastern spruce budworm is a native insect that is always present in our forests. Every 30 to 40 years, large outbreaks occur and can last for years, affecting millions of hectares.

By stripping and eating the tree needles (defoliating the tree), spruce budworm damages and eventually kills trees. This affects the economic, recreational and aesthetic values of the forest, impacting communities, the forest industry and the people who rely on this sector for their livelihood.

Spruce budworm: A major pest

Insect outbreaks are an important natural disturbance in Canada’s forests. Some affect small areas and have limited impact. In these cases, forest managers may let the outbreak run its course. However, when large outbreaks have the potential to affect millions of hectares of forest and cause extensive damage, forest managers may look for ways to control the spread and limit the impact of the outbreak.

Spruce budworm is the main defoliator of conifers (trees with needles) in Canada’s forests. In early spring, larvae (caterpillars) emerge from hibernation and eat the young needles on the trees. Around midsummer, the larvae become pupae, from which adult moths emerge about 10 to 12 days later. The moths then mate, lay eggs and sometimes move to new stands of trees.

Outbreaks of spruce budworm tend to be widespread and severe. The outbreak that ended in 1993 affected 52 million hectares (ha) in eastern Canada and the U.S. The current outbreak, which began in Quebec in 2006, had affected 7 million ha by 2015.

Tracking large outbreaks poses large challenges

Scientists are doing research to better understand spruce budworm ecology and options for managing outbreaks. For example, an early intervention strategy for New Brunswick is aiming to protect forests where communities live, work and play. Early intervention involves keeping budworm populations low by knocking down “hot spots” (areas with rising populations), slowing the spread of the insect and helping protect forests from the severe defoliation that a major outbreak would cause.

Scientists monitor populations of spruce budworm using traps that contain the insect’s sex pheromone, the chemical that the females emit to attract mates. By setting traps and then counting the number of budwormmoths that fly into them, the scientists can learn more about where, how and how quickly the outbreak is spreading. This also helps them identify the “hot spots” that may need to be treated.

But monitoring a large outbreak covering vast areas is challenging. This is where citizen science comes in.

Two photos comparing the flight of spruce budworm moths in front of cars in Campbellton, New Brunswick in 1957 and in 2016.
Spruce budworm outbreaks are cyclical: flights of moths in 1957 and 2016 in Campbellton, New Brunswick.

Citizen scientists gather data for researchers

Used in a growing range of fields, from biology and medicine to astronomy, citizen science involves volunteers gathering data to help scientists answer research questions.

In the case of the spruce budworm outbreak, an innovative project called Budworm Tracker is giving volunteers in eastern Canada the tools to gather and report data on spruce budworm populations – data that is helping scientists monitor and better understand the insect and its spread.

In this initiative, volunteers receive a free Budworm Tracker kit containing a pheromone trap, a data collection sheet and detailed instructions. They hang their trap from a lower branch of a spruce or balsam fir tree near where they live or work.

From mid-June until the end of the summer, these citizen scientists check the trap at least once a week, collecting and counting the moths and recording their findings. Volunteers with a smartphone can report their findings directly on the Budworm Tracker website or use a downloadable app. At the end of the summer, the volunteers mail the data sheet and the moths back to the researchers, who validate and analyze the data.

In this way, citizen scientists are giving researchers data on population numbers and on the timing, conditions and patterns of moth flights. Follow-up DNA analysis of the moths by the scientists also provides information about where the moths are coming from – in other words, how they spread.

By participating and contributing to real, on-the-ground research, citizens involved in Budworm Tracker are learning about both science and their environment. In the future, this model of citizen science could be used for research on other insect pests – an exciting prospect for citizens and scientists alike.

A satellite image showing the locations of Budworm Tracker traps in eastern Canada in 2016.
Locations of Budworm Tracker traps.

Budworm Tracker 2016: By the numbers

  • Number of traps sent to volunteers: 405
  • Number of volunteers who submitted data: 352
  • Return rate: 87%
  • Moths collected: over 16,000
  • Total days of data collected: 5,328
Photo of a girl looking into a Budworm Tracker pheromone trap for moths.
A young citizen scientist checks a Budworm Tracker pheromone trap for spruce budworm moths.

Healthy Forest Partnership. (accessed April 24, 2017).

Ministère des Forêts, de la Faune et des Parcs. 2016. Aires infestées par la tordeuse des bourgeons de l’épinette au Québec en 2016 (Version 1.0). Québec, QC: Gouvernement du Québec, Direction de la protection des forêts. (Available only in French.)

Morris, R.F. (ed.) 1963. The dynamics of epidemic spruce budworm populations. Memoirs of the Entomological Society of Canada 95 (S31), 7–12.

Pureswaran, D.S., Johns, R., et al. 2016. Paradigms in eastern spruce budworm (Lepidoptera: Tortricidae) population ecology: A century of debate. Environmental Entomology 45(6), 1333–1342.

  • For more information on the Budworm Tracker program, or to volunteer, visit: Budworm tracker
Photo credit
  • Vehicle in Campbellton, NB, covered in spruce budworm moths in 1957, from R.F. Morris, 1963.