Fake caterpillars scattered on trees around Montreal as part of biodiversity study

Montreal researchers are putting 800 fake caterpillars made out of modelling clay on trees around Montreal's southwest neighbourhood in an attempt to learn more about invasive species and biodiversity in the city.

The idea is to attract predators, like birds or spiders, to this easy-to-access fake prey. Then the researchers can examine the caterpillars that are left behind.

"We want to assess what type of predator is where in the city," said Alain Paquette, a biology professor at the Université du Québec à Montréal (UQAM), and one of two researchers leading the study.

"We also want to study how tree species affect the type of predators we encounter and if, in turn, their presence can help protect trees."

A lack of biodiversity can have significant consequences when invasive species, like the emerald ash borer, get involved.

The beetle that's native to Asia has had devastating effects in North America and has led to the deaths of millions of trees.

'In nature, everything is connected'

The researchers want to get a better grasp on factors that affect the health of trees in cities — places that hardly facilitate their growth.

"In nature, everything is connected," said Bastien Castagneyrol, researcher at the National Institute of Agricultural Research in France, which is managing the project on the other side of the Atlantic.

"The types of trees found in cities will influence the types of herbivores that populate them and, subsequently, the predators found," he said.

In Montreal, there are as many as 322 different species of trees — but 60 per cent of those trees belong to three main species: silver maple, Norway maple and ash.

If all goes well, the researchers are hoping to turn their study into a participatory science project by bringing in members of the public and students next year.