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Extension > Yard and Garden News > August 2017

Thursday, August 24, 2017

EAB found in Martin County

Jeffrey Hahn, Extension Entomologist

The Minnesota Department of Agriculture (MDA) reported earlier this week that emerald ash borer (EAB) was confirmed in Martin County in the south central area of the state on the Iowa border. Because the nearest infested areas in either Minnesota or Iowa are several counties away, the infestation is the result of someone moving infested ash into the county.
Watch for EAB galleries and other
symptoms of their presence.  Photo: Jeff
Hahn, University of MN Extension

EAB was first found in Minnesota in 2009. Since then, it has spread and is now found in 16 counties.  EAB is a very destructive invasive insect that threatens all native ash in the U.S. Ash is a very important resource in Minnesota where about 1 billion ash trees occur, one of the highest numbers of ash trees in the country.

People can greatly reduce the chance for EAB to spread by buying their firewood locally and avoid transporting it. Burn it where you buy it. It is equally important to observe any quarantine restrictions for the movement of any ash products that may occur in your county. Be aware of the symptoms of EAB and report any suspicious infestations to the MDA’s Arrest the Pest line at 1-888-545-6684 or arrest.the.pest@state.mn.us.

For more information about EAB, including symptoms of infestations, see Emerald ash borer in Minnesota.

For the original MDA news release, go here.

Wednesday, August 23, 2017

Add fall color and benefit butterflies by planting native grasses

Contact: Diane Narem, Horticulture Researcher, dmnarem@umn.edu

Although summer may be coming to a close, it’s not too late to add some charm and color to your
Little bluestem Blue Heaven™
garden this fall with some perennial native grasses. Native grasses can liven up a planting with their interesting shapes and seasonal color changes and benefit multiple types of wildlife, including butterfly and moth species.

According to U of M Extension Horticulturalist Mary Meyer, native grasses require one month of good growing conditions to establish in the fall. This means you can safely plant grasses until mid-September. Extra watering may be necessary during hot or dry spells in the fall. Container plants with well-established root systems are the best choices for fall plantings.

“Many grasses are just beginning to flower in August," Meyer said. "They will soon start their fall color change, so August and early September can be peak season for native grasses".

Not only do they add beauty to your landscape, but grasses are also low maintenance and provide benefits to the environment. Once established, native grasses need little additional water because they are naturally drought tolerant. They also do not require fertilizer or added nutrients. They minimize soil erosion and increase organic matter, creating better soil conditions.

Native grasses provide habitat for wildlife, such as birds, native bees, and butterfly and moth larvae. Many species of butterflies and moths use native grasses as host plants during their caterpillar stage. The larva feed on native grasses, and some build shelters in the leaves and stems, while others hide at the base of the plant. Many of these species survive winter as larva and take shelter within grass plants or burrow just below the soil surface.

Native grasses that provide fall color and food for butterfly and moth larva include little bluestem, big bluestem, switchgrass, and Indiangrass. You can find these plants and others at garden centers throughout Minnesota. For more information on native grasses from the University of Minnesota Extension: Ornamental Grasses for Cold Climates

Friday, August 4, 2017

Cicada killers common now

Jeffrey Hahn, University of Minnesota Extension

A large solitary wasp called a cicada killer, Sphecius speciosus, is common in many areas of Minnesota now. It ranges in size from 1 – 1 ½ inches long. It has a black abdomen with yellow bands, a reddish brown thorax with reddish brown legs and amber colored wings.
Cicada killer with a captured cicada.  Jeff Hahn, U of M Ext.

Some people mistakenly believe they have found a European hornet which is also a large wasp. However, European hornets are social insects living in nests they usually build in tree cavities; they can also be found within homes and other buildings. European hornets do not occur in Minnesota.

Cicada killers nest in the ground, typically in well-drained, light soil exposed to full sun. They are a solitary wasp, meaning that there is only one wasp per burrow. However, cicada killers are gregarious, so there are typically many of them in a small area.

These wasps prey on cicadas. Cicadas are stout, winged insects that are common during the summer. A cicada killer uses her stinger to paralyze a cicada she captures. She carries it back to her nest where it is food for her young. Once the larvae are full grown, they pupate and remain in their burrows until next year.                    

Despite their size, cicada killers are not dangerous to people. Females have stingers but they are not aggressive and ignore people. They do not have an instinct to protect their nests (like yellowjackets and honey bees) and you can walk among them with little worry. Of course, if you provoke a cicada killer or it feels threatened, it can sting to protect itself.
Cicada killer nests can become very abundant in a small area. 
Jeff Hahn, University of Minnesota Extension

Fortunately, cicada killers are just annoying. Their tunneling can be unsightly but does not kill lawns. It is not impossible for their burrowing activity to undermine patio bricks but that is not common.

If you have cicada killers nesting on your property, there are a couple of options to consider. The first is to ignore and tolerate them and let them run their course. Remember, there is very little risk of stings and they will go away on their by the end of the summer. The area can be roped off, in necessary, to keep people away from the nests.

Another option is to treat the nests. Treating the general area is not very effective. Instead, apply an insecticide into each individual nest entrance. Dusts are most effective, although sprays can help reduce numbers. Be sure the product you use is labeled for you use on turf. Effective active ingredients include permethrin and carbaryl. You can also hire a lawn care company to treat the cicada killers.
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