In this post, we’re continuing to count-down 2015’s top insect trends in the state. This is the final post in a three part series. Part I (2015’s diagnostic lab statistics) can be found here and Part II (Top Insect Trends Numbers 10-6) can be found here.
With all the headlines about bees, it’s not surprising to see pollinators in the top insect stories again in 2015. Similar to other years in the recent past, honeybees and other pollinators have been facing declines. Unfortunately, Wisconsin saw some of the highest honeybee losses in the country, with over 60% colony loss during the 2014-2015 period. Some good news over the past year has been the development and release of pollinator protection plans. A federal pollinator protection plan was released in May with the goals of reducing honeybee losses, increasing the population of Monarch butterflies, and increasing pollinator habitat. In addition, a Wisconsin pollinator protection plan was announced in 2015, and was just released in January of 2016. Due to the recent declines and their importance to agriculture in the state and nation, pollinators will continue to be in the spotlight in the future.
4) Spring caterpillars
An unexpected insect trend in the spring of 2015 was the surprising abundance of a number of caterpillar species feeding on plants in the landscape. Caterpillar species, such as the humped green fruitworm, speckled green fruitworm, eastern tent caterpillar, forest tent caterpillar, gypsy moth caterpillar, and the euonymous caterpillar are typically present to some extent, although their numbers have been low the past few years. For a number of potential reasons, these species had a great spring and during a period in May and June, caterpillars made up roughly 30% of the cases coming in to the diagnostic lab. Weather patterns (i.e., rainy weather) and natural predators/parasites/diseases can have significant impacts on caterpillar populations each year, so it’ll be interesting to see if we’re faced with a plethora of caterpillars again in 2016. Additional details of this story were featured in a blog post last June.
3) Viburnum Leaf Beetle
In terms of a new emerging pest with the potential to impact a commonly planted landscape shrub, Viburnum Leaf Beetle is near the top of the list. As of late 2014, we only knew of a single infested viburnum bush in northern Milwaukee County, which raised the question: is the infestation small enough to contain and/or eradicate? Some ground truthing this past spring identified many new infestations in SE Wisconsin, in many cases miles from the original site. At the moment, the viburnum leaf beetle seems to be centered around the four county area where Milwaukee, Waukesha, Washington, and Ozaukee counties meet. While this insect only feeds on viburnums (and related plants like Arrowwood), the damage can be significant. It may be some time before this pest spreads elsewhere in the state, but if you have viburnum plants in your yard in SE Wisconsin, be weary! Additional details of this case were featured in a post last June.
2) Brown Marmorated Stink Bug
Populations of the invasive Brown Marmorated Stink Bug increased dramatically in 2015 and this insect takes the overall #2 spot in this list (up from #8 last year). This invasive species was first spotted in the state in 2010, and each year a handful of lone adults have been found in Wisconsin. In the fall of 2015, we had more sightings of BMSB (30+), than in the past 5 years combined! (Spoiler: this trend has continued into early 2016) At this point, the “hot spots” in the state are: Dane County, the greater Milwaukee area, and the Fox River Valley. In addition to being an indoor nuisance pest, BMSB can also feed on and damage a wide variety of plants in home gardens, agricultural fields and orchards. In other places in the country, the first reports of plant damage have typically been noted ~3-5 years after the initial detection of this species. With that said, 2016 could be the year that BMSB really takes off and starts wreaking havoc for gardeners and agricultural growers alike. Additional details of this case can be found in this post from last October.
1) Magnolia Scale
While scale insects have already been mentioned in the “sucking insects” section (#9 on the list), one species in particular, the Magnolia scale (Neolecanium cornuparvum), seemed to stand out amongst all other insects in 2015. This species is often present in low numbers in the state, but the conditions must have been perfect for their populations to explode last year. During the months of June and July, reports of Magnolia scale were coming in on almost a daily basis. Being one of the unusual scale insects, Magnolia scale adults look more like a fungus than an insect (note the whitish blobs in the image below). Not only did this bizarre looking species pummel Magnolia shrubs and trees in many parts of the state, but the honeydew produced by these insects rained down below, attracting ants and yellowjackets and leading to the growth of unsightly black sooty mold. A number of predators, parasites, and diseases typically keep Magnolia scale in check, but with the extremely high infestations noted last year, it’s likely that we’ll continue to see some Magnolia scale activity into 2016. If you experienced magnolia scales first hand, there’s a helpful factsheet available here.