Expert explainer: How the spotted lanternfly could wreak havoc on Canadian farmers  

Prof. Amanda Roe answers questions on how the invasive species could affect agriculture and how the public can help 

 November 15, 2022

 November 15, 2022

The spotted lanternfly has recently been discovered within five kilometres of the Canadian border. While it is a striking looking insect, it poses a significant threat to agriculture in Canada, especially in southwestern Ontario.  Amanda Roe, federal research scientist with Natural Resources Canada (NRC) and adjunct biology professor at Western, explains why the spotted lanternfly is such a concern and gives tips on how the public can help contain its spread.  

Roe is an expert on invasive insects including the spotted lanternfly. As a research scientist with Natural Resources Canada, she is working with the Canadian Food Inspection Agency and U.S. partners to study this invasive pest, assess its risk to Canada and identify factors that might limit its spread north.  

What is the spotted lanternfly? 

The spotted lanternfly (Lycorma delicatula) is one species of a larger group called fulgorids or lanternflies. They are what we call a true bug (family hemiptera) and they have sucking mouth parts that can pierce plant tissue and suck out  sap, just like a mosquito does to humans.   

What does your study of the insect focus on?  

I focus on how they respond to winter and winter temperatures. They overwinter as eggs and winter temperatures can be lethal. I want to know how much cold they can handle – we are in Canada after all. I am also interested in whether this cold tolerance may vary between populations and whether those populations vary genetically.  

When an invasive species arrives in a new environment, it encounters new climates, habitats and predators. We don’t necessarily know exactly what happens when a new population establishes itself, but we know based on the individuals that survive  they can begin to evolve and adapt to this new location.  

I was brought on by NRC to study the spotted lanternfly based on my earlier work with Brent Sinclair (biology professor) at Western. We collaborated to understand the cold tolerance of the Asian longhorn beetle. Much of what I am doing with the spotted lanternfly was initially developed on this earlier project so we are taking these tools and approaches and applying it to this new invasive species. We’re really at the beginning of this work.  

What dangers does the spotted lanternfly pose to Canada? 

The spotted lanternfly poses a significant threat to Canada’s agricultural industry. Vineyards and fruit orchards are at the greatest risk. It is predicted that billions of dollars are at risk if spotted lanternflies were to invade southern Ontario.  

It sucks sap from a wide range of plants. This pest has a broad host range, which means it can damage a lot of different plants. Young stages of the insect feed heavily on grapevines and fruit trees. However, they also feed on maple, pine, oak, walnut and poplar. Adults prefer the tree of heaven, another invasive species. Like aphids they exude a very sugary excrement (called honeydew) which can cause mould to grow on host plants, which is an additional problem. Infestations can have thousands of individuals, which can cause enough damage to severely weaken or kill host plants.  

What factors  are aiding their spread?  

The tree of heaven is an important final host plant which the insect uses to complete development. Having tree of heaven on the landscape increases the chances of spotted lanternflies establishing a breeding population in a new area. It’s an interesting example of one invasive species helping another. 

Second, adults prefer to lay eggs on smooth surfaces, and these are very difficult to spot due to their cryptic grey colour. This can include trees and rocks, as well as any artificial surface (e.g. camping gear and vehicles). These can be easily transported out of infested areas if not properly inspected. Nymphs and adults are also good hitchhikers and can be transported long distances on vehicles.  

Third, climate change is altering the risks invasives pose to Canada. We know these insects require specific temperature conditions to survive winter and cold conditions can help limit their northern spread. However, recently we have been experiencing progressively warmer winters, allowing new species to establish further north than ever before.  

We also cannot assume that this invasive species won’t adapt to new, colder conditions. In another collaboration with Professor Sinclair, we observed the emerald ash borer, another invasive species, could survive extreme winter conditions in Winnipeg, despite earlier evidence to the contrary. This study highlighted the adaptability of an invasive species to extreme temperature conditions, and how it was about to withstand new external conditions.  

Where have they been found? 

Spotted lanternflies are native to China but have become invasive throughout the eastern U.S. They were initially found in Pennsylvania in 2014 and have spread to neighbouring states with new detections this year in Buffalo, N.Y. and lower Michigan, bringing them very close to the Canadian border. We anticipate they could be spotted in southwestern Ontario at any time. There is a multi-agency task force that is preparing to respond when they are found in Canada. We have intercepted them in the past, but an established population has not been found. 

What do they look like? 

Egg masses are very cryptic and look like really old, grey chewing gum, and they’re just sort of stuck onto surfaces.  The insects like to lay on the sides of trees, hence the importance of not moving firewood. Adults and nymphs are brightly coloured and easily distinguished from native insects.  

What can be done to prevent their spread? 

The general public has an important role to play in detecting this new invasive species. First, egg masses are often laid on trees or plant stems, so firewood and plant material are an important source of invasive populations. Like many other invasives, firewood is an important spread pathway, so not moving firewood is a huge help to limiting invasive spread. It is best to burn firewood where you buy it. 

Transportation corridors have been identified as a critical pathway for the spread of this invasive species. Billions of dollars of goods move through southwestern Ontario, so the risk of spread is high. It’s impossible to inspect everything, which is why it’s so important for the general public to be aware of what they are looking for. The sooner we find new infestations, the more likely we will be able to eradicate these insects. 

It is highly probable that a non-expert outside enjoying the environment will be the first to detect spotted lanternflies. The Canadian Food Inspection Agency has developed posters and fact sheets that will help the public identify this new species if they come across it. Take a picture and share it with experts at  These actions have a huge impact on our ability to respond to these new species.  



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