The walnut twig beetle is as small as a grain of rice, but healthy walnut trees can be quickly felled by the disease it spreads: thousand cankers disease.
The emerald ash borer is less than a half-inch long, but it can take down healthy ash trees.
State entomologists and arborists fear the tiny insects will do to the trees of Kansas what zebra mussels are doing to Kansas lakes.
"They are invasive and they are pests," said Raymond Cloyd, a specialist in ornamental and horticultural entomology and pest management at Kansas State University.
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The insects pose such a threat that the state's Agriculture Department along with the Kansas Forest Service and Kansas State University are holding pest-detection workshops this week to help people identify the bugs and the hazards they carry. The workshops in Wichita today and in Lawrence on Wednesday are designed to alert Master Gardeners and city foresters to the symptoms of infected trees.
It is important for people to be aware of these insects and the harm they can pose in order to defend against infestations, said Tim McDonnell, community forestry coordinator for the Kansas Forest Service.
"People have compared the damage these insects can cause to the dutch elm disease," McDonnell said.
The emerald ash borer is native to eastern Russia, northern China, Japan and Korea. In 2002, it was detected in Michigan and may have been accidentally brought over in packing and shipping containers from Asia, McDonnell said.
The borer attacks ash trees and has already destroyed millions of ash trees in several states, including Missouri.
The walnut twig beetle is native to North America but has been primarily contained — until the past few years in the western Untied States.
Both the emerald ash borer and the walnut twig beetle are rapidly spreading into other states.
"Our fear is that they may be coming across Kansas," McDonnell said. "We don't want to cause a mad scare ... but we'd like people to be aware. If it shows up in Kansas, perhaps we can contain an outbreak."
The insects are often spread through firewood and contaminated nursery stock, Cloud said. They can also latch on to pallets and crates.