Wisconsin homeowners are warned to watch out for scam artists taking advantage of an invasive pest that could be in your trees.

Extension Agents say the Emerald Ash Borer is responsible for killing ash trees in southeast Wisconsin.

And the state says when the bugs show up, so do scammers, looking to take your money.

It's a tiny green beetle, tearing through trees and now people's wallets.

Randy Niederkorn says, "Undoubtedly unscrupulous businesses are going to emerge to try to take advantage of people. We want to warn people to be aware of those types of businesses."

The state says its seen this type of scam before when parts of Wisconsin were infested with gypsy moths.

Unlicensed pesticide applicators go door to door, offering to protect your trees.

Consumer Protection's Randy Niederkorn, says there are some steps you can take to protect yourself, and that includes not hiring someone who knocks on your door.

Randy Niederkorn says, "We recommend that you hire a reputable applicator with whom you're familiar."

And he says you have every right to ask questions before you hire any company.

Randy Niederkorn says, "Ask for references of the applicator, ask if they carry liability insurance, and ask for the brand name or product name of the product that's going to be sprayed on the trees."

Niederkorn says to be wary of companies who claim 100% success with the products they're using.

Randy Niederkorn says, "We want to make sure that what is being sprayed on the trees is going to be an appropriate application."

If you ask, Wisconsin law requires companies tell you what they're putting on your tree and what the hazards are.

Niederkorn recommends you ask those questions.