SPRINGFIELD, Ill. (AP) – Illinois lawmakers have approved a plan proponents say will help protect the habitat of monarch butterflies.

The proposal would prohibit counties and towns from classifying milkweed as noxious or exotic weed. Milkweed is a primary food source for monarch larvae.

Backers say it’s vital to plant more milkweed, not ban it.

Environmental experts say over a dozen Illinois cities classify milkweed as noxious.

However, some opponents say local communities should be able to decide whether to ban it.

The Senate approved the plan 41-6 Tuesday. It’s headed to Gov. Bruce Rauner’s desk.

Sen. Melinda Bush, a Grayslake Democrat, was a sponsor. She says Illinois has a unique relationship to the insect and they should be protected.

Monarchs were named Illinois’ official insect in the mid-1970s after school children lobbied for the designation.

The bill is HB0685.