Be on the lookout for invasive lady beetles

MISSOULA, Mont. — Gardeners who use ladybugs for pest control may want to take a closer look at which species they are bringing home.

Glenn Marangelo, development director at the Missoula Butterfly House & Insectarium, explained that Montana has many species of ladybugs, formally known as lady beetles.

“We've got over 45 species of lady beetles in Montana, which is really amazing when you think about it. We've got two that are non-native, the seven spotted lady beetle and the multicolored Asian lady beetle,” said Marangelo.

He said those two non-native species are now present on every continent except Antarctica. Marangelo also explained that their presence hurts native lady beetles in Montana.

“The problem is they're aggressive enough that they're out competing and also consuming other beneficial native insects. So, there's always that catch-22 introducing something to do something of benefit. There's sometimes unintended consequences,” said Marangelo.

Which hints to why they are here in the first place.

“They were introduced to the United States in the early 1900s, and it was because they're such aggressive eaters to control aphid numbers for, probably mostly, agriculture. So, crops and things like that. They're still sold as a form of pest control,” said Marangelo.

For people buying lady beetles for a garden, Marangelo said it is important to look for native species such as convergent lady beetles rather than seven-spotted or multicolored lady beetles.