Asian Longhorned Beetle
Although the Asian Longhorned Beetle (ALB) was discovered attacking trees in the Chicagoland area, there has been no ALB spotted within the limits of Northfield Township or the surrounding communities. Native to parts of Asia, the beetle is believed to have arrived in North America in the wooden packing material used in cargo shipments from China. Local authorities have acted quickly to stop the infestation of the ALB from spreading.
The ALB primarily attacks healthy maple trees, but infestations have also been discovered in horsechestnuts, poplars, willows, elms, mulberries and black locusts. Currently, there is no known chemical or biological defense against the ALB and in North America they have few natural predators. In all cases of infestation, the affected trees are cut down and the wood chipped or burned. Cutting down an infested tree and improperly moving the wood which contains maturing ALB increases the speed and will broaden an infestation. Please call the Road District if you suspect an ALB infestation.
Early detection of infestations and quick treatment are crucial to successful eradication of the ALB.
What Does it Look Like?
Mature ALB are very large insects with bodies ranging from 1 to 1 1/2 inches in length and antennae which can be as long as four inches. The shiny jet-black body has white spots on the back and long distinctive antennae banded in black and white. The feet and antennae may have a bluish tinge. The ALB has wings and can fly, although only for short distances because of their size and weight.
What Do I Look For?
- Oval to round pits in the bark. These egg-laying sites or niches are chewed out by the female ALB, and a single egg is deposited in each niche.
- Oozing sap. In the summer, adult female ALB chews holes in the bark of the trees to lay their eggs. After hatching, the white, wormlike immature ALB bores into tree trunks and branches, causing sap to flow heavily from wounds, as the larvae feed inside the tree.
- Accumulation of coarse sawdust around the base of infested trees, where branches meet the main stem, and where branches meet other branches. This sawdust is created by the ALB larvae as they bore into the main tree stem and branches.
- Round holes, 3/8 inch in diameter or larger, on the trunk and on branches. These exit holes are made by adult ALB emerging from pupation sites by chewing their way out from the tree, leaving behind the exit holes.
- Unseasonable yellowing or drooping of leaves when the weather has not been especially dry. These symptoms show up when the immature insects, growing inside the tree, have bored through tissues that carry water and nutrients to the canopy above. Repeated attacks can lead to dieback of the tree crown and, eventually, death of the tree.
When is it the Most Active?
Adult ALB are present from June to October, but can be found later in the fall if temperatures are warm. The ALB usually stays on the trees from which they emerge, but are capable of moving a short distance from the host to feed and reproduce. Each female is capable of laying 30 to 70 eggs. The eggs hatch in 10 to 15 days and the larvae tunnel under the bark and into the wood where they eventually pupate. Emerging from pupation sites, the ALB bores a tunnel in the wood creating a round exit hole in the tree.
How Can a Homeowner Help?
If you detect the presence of the ALB, contact the Northfield Township Road District at 847-724-7055 so that we can take the necessary steps to contain the infestation. Remember, the only way to battle the ALB is to destroy the infested trees. Cutting down mature trees is a heartbreak, but it is preferable to permitting the infestation to spread.