ST. PAUL  (AP) - Researchers will be hanging thousands of purple traps across Minnesota this summer in search of the emerald ash borer.

The Minnesota Department of Agriculture plans to place 4,500 traps starting this week. The purple, prism-shaped sticky traps are scented like distressed ash trees to attract the metallic green beetles, which have killed tens of millions of trees in other states. They first turned up in Minnesota in 2009.

The state wants to get a better handle on where ash borers are present so it can decide if further steps are needed to slow their spread.

Geir Friisoe of the Plant Protection Division says the traps are one of the only detection tools they have. He says it's important that people don't disturb the traps so researchers can collect accurate data.

(Copyright 2011 by The Associated Press.  All Rights Reserved.)

More From AM 1240 WJON