• Damages Landscapes

• Summer

In May 2009, the emerald ash borer was confirmed in Minnesota. Because these beetles can wipe out all infested ash trees, it is our responsibility to work together to stop the aggressive movement of this invasive pest towards our parks, nurseries, forests, streetscapes, and backyards.

Unfortunately, emerald ash borers easily spread either naturally (adult beetles can fly and to new areas) or by human assistance through the movement of infested ash logs from affected areas to neighboring places.

HOW DO I KNOW IF I HAVE EMERALD ASH BORERS?

• Larvae bore through the bark and into the cambial region making S-shaped feeding gallery becoming progressively wider as the larva grows. Galleries weave back and forth across the wood grain.
• Due to larvae feeding, canopy dieback begins in top one-third of canopy and progresses until the tree is bare.
• Adult beetles leave distinctive D-shaped exit holes in the outer bark of branches and the trunk.

 Other signs of possible EAB infestation include:

• The sprouting of epicormic shoots around the base of the tree or at the junction of live and dead parts of the trunk or branches.
• Leaves of infested trees often look larger than normal.
• Vertical cracks or spilt on bark due to callous tissue formation. Usually under this spilt, galleries are exposed.

WHAT DO EMERALD ASH BORERS LOOK LIKE?

• Adult emerald ash borers are about 3/8” to 5/8” in length

• Emerald ash borers have a flattened back with metallic green wing covers, and coppery red or purple abdominal segments beneath the wing covers.

• Emerald ash borer larvae are creamy white, legless with flattened, bell-shaped body segments. The terminal segment bears a pair of small appendages.

ARE EMERALD ASH BORERS DANGEROUS?

No, emerald ash borers do not bite or sting humans nor do emerald ash borers spread any disease-causing organisms.

CAN MY HOUSE BE DAMAGED BY EMERALD ASH BORERS?

• The emerald ash borer poses a very serious threat to all species of ash trees throughout the United States and Canada.

• Emerald ash borers will not cause damage to your house, but anyone with ash trees on their property should be aware of this serious pest.

• During the relatively short time that the emerald ash borer has been in North America, it is believed to have killed millions of trees in the United States and Canada, with billions more across North America at risk of infestation and death.

• Emerald ash borer larvae live inside a tree and eat through the active phloem and xylem of the ash tree.  This causes general yellowing and thinning of the foliage followed by canopy dieback and the eventual death of the tree in one to three years.

• Emerald ash borer adults do not tunnel inside a tree.

• After emergence from a tree trunk; adult emerald ash borers typically fly within a ½ mile from their emergence tree to feed on the leaves of another ash tree and lay eggs.

• However, they can fly up to 10 miles, especially when ash trees are not available within their normal flying zone.

WHY ARE EMERALD ASH BORERS IN MY YARD?

If you have any species of ash tree on your property and are within 10 miles of a known emerald ash borer infestation, your property is susceptible to an emerald ash borer infestation.

Adult emerald ash borers fly to ash trees to eat and lay eggs.

Emerald ash borers only attack ash trees; other species of trees are safe from infestation.

WHAT DO EMERALD ASH BORERS EAT?

• From mid-May to mid-August, adult emerald ash borers are active and feed on ash foliage leaving small, irregularly shaped patches along the leaf margins.

• However, adult emerald ash borers’ feeding causes little damage to the tree.

• After hatching, the first instar larvae tunnel into the tree and feed on tree’s phloem for several weeks, creating S-shaped galleries packed with fine sawdust-like frass (larvae debris).

• As the emerald ash borer larga grows, its gallery becomes increasingly wider. 

WHAT IS THE LIFECYCLE OF EMERALD ASH BORERS?

• Generally, adult emerald ash borers live a total of three to six weeks.

• During this period, male and female emerald ash borers feed for a few days prior to mating.

• The feeding is continued for an additional 1 to 2 weeks before females actually begin laying eggs.

• A female emerald ash borer can mate multiple times during her lifespan and lay from 30-60 eggs.

• Eggs are deposited individually on the surface of the bark, in bark crevices or under outer bark or branches.

• After depositing, eggs soon darken to a reddish brown, and hatch in 7 to 10 days.

• Larval feeding is usually completed in autumn and pre-pupae overwinter in cells found about a half-inch into the sapwood or outer bark.

• Pupation usually takes place when it begins to warm up in April or May.

• It takes two to three weeks for emerald ash borer pupae to become adults, but adults often remain in the pupal chamber or bark for one to two weeks before emergence.

• From May to early July, adult emerald ash borers chew a distinctive D-shaped exit holes in the bark and emerge from the ash trees.

• In northern states, a two-year lifecycle can occur in newly infested ash trees that are relatively healthy; whereas in stressed trees, the lifecycle takes only a single year to complete.

WHAT OPTIONS DO I HAVE FOR TREATING MY ASH TREES?

• Since emerald ash borers are not native to North America, our ash trees have little natural resistance to this pest.

• If you choose to treat your ash trees, there are a variety of insecticide treatment options available and research has shown that treatments can be effective.