Bugs in Review

11/17/11
Newsletter Topics

#1 - Tips of the Week

#3 - More Denny's Tips

#5 - Bugs - Yr in Review

#2 - Plants of the Week

#4 - Putting Perennials to Bed

Bugs - Year in Review

Taken from The P.E.S.T. Newsletter
PEST EVALUATION AND SUPPRESSION TECHNIQUES
Editor: David Shetlar (THE BUGDOC)
Landscape Entomology Extension Specialist, The Ohio State University Extension

Traditionally, I've reviewed the pests that I've seen this last year and I've even gone so far as to designate the top pest of the season. I'm having a hard time selecting any one "spectacular" pest this season, so I'm going to reserve the right to not award this designation this year!)

Invaders:
We continue to see the spread of the emerald ash borer and even though the ODA declared all of Ohio's 88 counties as being infested, there were only four more counties added to the known-to-be-infested list which leaves about 30 counties where the beetle has not been found. These counties are mainly in the east-central part of the state. By declaring that the state is generally infested, the restrictions about moving wood products from a quarantined county into a non-quarantined county were removed. With a third of the state not experiencing this pest, especially in the counties that have major forests, we have not seen the eventual impact of this pest! Columbus is in the middle of major EAB attack, yet there are still plenty of ash trees surviving, but an experienced eye tells me that most of these trees will disappear next year! Stay tuned.

Adult Emerald Ash Borer on Leaf

The second major borer story is the discovery of the Asian longhorned beetle in the Bethel, Ohio area! The beetle was confirmed in June and the USDA with ODA immediately clamped a quarantine on several townships in and around the Bethel area. Over the summer, extensive sampling was undertaken and the quarantine area was expanded slightly because infested wood was thought to have been moved out of the area and when the new location was inspected, voila!, a spot infestation was found! It's been very interesting seeing the inspection and detection process proceed and how meticulous these folks are in tracking down all the possible movements of the beetle. Even so, the infestation is small enough to be contained and eradicated over the next few years. In any case, this find should remind us all that the potential of transport of this beetle and other invaders is constantly with us. We all need to be on the lookout for anything that seems to be out of the norm! I'd rather someone ask a question and have us confirm that the suspect is nothing new than let an invader get a foot-hold and expand to a point that it is impossible to stop!

Asia longhorned beetles are large and impressive beetles!

The viburnum leaf beetle continues to expand in the Cleveland, Akron and Canton areas, basically all of the far northeastern counties. This pest has virtually destroyed the value of many landscape viburnum species, ones that used to be relatively pest free plants. The major viburnum being attacked is the native arrow-wood viburnum that has served as a great understory plant! This pest can be controlled, but it usually takes one well timed application of a systemic to take out the larvae, then two or more foliar applications to take out the adult beetles that readily fly to new locations to feed. These adults eventually lay eggs by chewing holes into the small stems of susceptible viburnum. This egg laying then kills these small branches! If not controlled, attacked plants are whittled down to nothing in three to five years.

Viburnum leaf beetle larvae skeletonizing a leaf.

The gypsy moth seems to have been slowed, primarily due to the wetter and cooler than normal spring weather. When we get this kind of weather, the caterpillar-killing fungus, Entomophaga, kills the caterpillars before they can mature. Yeah for biological controls, at least in cool, wet weather!

I'm not sure I can honestly include the annual bluegrass weevil as an invasive, but it appears to be behaving as one. This small weevil is actually a native of North America, but damage caused by it on managed turf has been primarily limited to the New England states. However, over the last two decades, damage has been detected in western Pennsylvania. Over the last couple of years, the damage from this pest has been confirmed in some eastern Ohio counties and on golf courses bordering Lake Erie! Whether the damage from this pest was just missed or is new is irrelevant to the poor golf course superintendents that have to deal with the damage! Being a pest new to Ohio, we are still trying to figure out the pest management practices that will keep the golf turf playable!

I've already talked about the brown marmorated stink bug, but I want to mention it again here! This pest will likely not be a major landscape plant pest though it will likely feed on the fruits of crabapples, callery pears and other trees and shrubs that we use for their ornamental value. This pest will be a major problem for Ohio's tree fruit growers and I've heard of considerable damage done to tomatoes, especially in back yard gardens!

I didn't cover the spotted-wing drosophilid fly which is still another new invasive pest. This is in the same genus as our common fruit fly, but this fly readily attacks fruits that have not become over-ripe! It was detected in southern Michigan last year and many suspect that it is in Ohio! This pest is a major destroyer of cultivated raspberries, blueberries, strawberries, grapes and cherries, just to name a few! This pest will make many of our fruits much more expensive to produce and backyard gardeners will be at a major loss for producing usable fruit!!

Foliage-Feeding Pests:

Compared to last year, many of our early season caterpillars were AWOL and many of the butterfly watchers noted that the common butterflies were later than normal this year. Last year, I saw hundreds of tiger and black swallowtails in June and July. This year, I didn't notice them until August and there were never the number seen last year. The early-season tent caterpillars were present, but not overly abundant, but the fall webworms really took off in July and seemed to attack all possible, susceptible trees by the end of August. It appeared that there may have been three generations of the fall webworm, but it was most likely a prolonged emergence of the summer adults that kept laying eggs! In central Ohio, the fall webworms were not noticed until late July when they picked up steam and began to turn the tops of honeylocust trees brown.

Fall Webworm nests in Trees

Other common defoliators, like the hickory tussock moth, the walnut caterpillar and yellowneck caterpillar, were also late this year and I was pretty surprised to see some major defoliation from these pests until late August! The Ohio foresters noted several oak forests that had been skeletonized by the scarlet oakslug sawfly. I didn't notice the damage in landscapes until late August and early September. Normally, this pest causes its damage in late June into July!

Bagworms were definitely down in the southern half of Ohio, but localized infestations were commonly missed until late August! I continue to be amazed at how folks can miss their evergreens turning steadily brown!

Beetle defoliators included the black locust leafminer. The mines of this little beetle are usually not noticed, but the skeletonization by the new adults turned black locust trees brown all across Ohio. Again, much of this damage seemed to be delayed two to four weeks later than normal. Conspicuous by their absence was the Japanese beetle adults. I heard of a few local problems, but over most of Ohio, they were largely unnoticed!

Oakslug sawfly larvae skeletonizing leaf!

Sucking Pests:

Aphids, soft scales, plant hoppers and leafhoppers were generally down this season! Again, I suspect that the major reason was the intense early rain followed by hotter than normal conditions in July and August. There were some localized outbreaks of the summer leaf aphids (on oak, maple and tuliptree), but most of the aphid attacks seemed to occur late in August.

The lace bugs were also late getting started, but the hawthorn, walnut, sycamore and oak lace bugs made up for lost time during the heat of July and August.

Planthopper nymphs and adult on shoot.

Leafminers:

The sawfly leafminers, mainly the elm and hawthorn species, were pretty spectacular this spring! The elm leafminer damage was aggravated by attacks of the elm flea weevil. Both pests are severely attacking the new hybrid elms, often causing so much foliage damage that they look like they are severely diseased!

The boxwood leafminer continued its defoliation of boxwoods and the infested leaves observed this month suggest that they will have another banner season next spring!

The birch, holly and inkberry leafminers were generally down this season.

Hawthorn leafminer damage.

Other Borers:

The twolined chestnut borer continues to be a major issue in recently transplanted oaks which are being used to replace the lost ash trees! The locust borer and hornbeam borers, also Agrilis species, continue to attack recently transplanted trees and are likely the major reason for failure of these trees!

Clearwing borers continue to be an issue, but we are learning about some new pesticide that will take out these caterpillar borers that the neonicotinoid insecticides didn't touch. More next year!

Lastly, the white pine weevil damage was down this year, but still present. I suspect that the spring rains didn't help the overwintered females in their egg laying efforts!

Pine damaged by white pine weevils!!