US

Use of parasitic wasps to fight ash borer grows to 24 states

FILE- In this undated file photo provided by the Minnesota Department of Natural Resources, an adult emerald ash borer is shown. Millions of tiny wasps as small as a grain of rice have been released into wooded areas in 23 states as the battle against the emerald ash borer turns biological. The U.S. Department of Agriculture has researched and approved for release in the U.S. four species of parasitic wasps that naturally target the larval and egg stages of the ash borer. (Minnesota Department of Natural Resources via AP, File)

FILE- In this undated file photo provided by the Minnesota Department of Natural Resources, an adult emerald ash borer is shown. Millions of tiny wasps as small as a grain of rice have been released into wooded areas in 23 states as the battle against the emerald ash borer turns biological. The U.S. Department of Agriculture has researched and approved for release in the U.S. four species of parasitic wasps that naturally target the larval and egg stages of the ash borer. (Minnesota Department of Natural Resources via AP, File)  (The Associated Press)

Millions of tiny wasps that are natural parasites for the emerald ash borer have been released into wooded areas in 24 states as the battle against the tree-killing borer is now biological.

The U.S. Department of Agriculture has researched and approved for release four species of parasitic wasps that target the larval and egg stages of the ash borer. Government agencies estimate the borer has killed nearly 38 million ash trees in urban and residential areas at a cost of nearly $25 billion.

The wasps, one so small it looks like a pepper flake on a white surface, lay eggs inside borer eggs or larvae preventing them from maturing.

Iowa is the 24th state to have wasps introduced in ash borer infested areas. Texas and Georgia will get them soon