Pesticides don’t just kill off bugs. They can also change their personalities.

Spiders have distinct personalities, according to McGill University researchers, dictating how they behave in certain situations. A bold spider will try to attack its reflection in a mirror, while a shy spider will slink away. As part of a study published in Functional Ecology, these researchers found that after exposure to the pesticide Phosmet, the behavior of bronze jumping spiders changed. 

The spiders, which eat pests in orchards and fields, became more unpredictable in their behavior after exposure to the insecticide, though some spiders seemed more sensitive to it than others. Male spider behavior mainly changed in regards to the way they explored their environment, while female spiders had more trouble capturing prey after exposure. 

“Farmers spray insecticides on the plants to get rid of these same pests, and it was thought that it had little significant effect on the spiders’ behaviors,” study author Raphaël Royauté, a former PhD student at McGill, said in a press statement. “But we now know that this isn’t the case.”

The study suggests that agricultural researchers may need to pay more attention to how pesticides affect other flora and fauna within an ecosystem.