As we head towards Labor Day and the unofficial end of summer, people are noticing some our different species of stinging insects. The inquiries we have received have all focused on these insects being Asian giant hornets (aka the “murder hornet”), an insect not known to occur in the state. Thus far, that species has only been found in the Pacific Northwest.
What we do have in Kentucky are things like yellowjackets, paper wasps, and European hornets. Some of these are aggressive in their own right, and others do resemble the Asian giant hornet. Here are some tips on identification and advice on managing these insects, if necessary.
Yellowjackets are some of the most encountered stinging pests. These bright yellow and black-colored wasps are usually around a half inch long. The workers of a colony are the ones we encounter most often. In the earlier part of summer there are fewer workers, and they are on the hunt for meat, which they can obtain as prey items such as caterpillars or as scavenged material from garbage and roadkill.
Yellowjackets build papery, football shaped nests in the soil or in shrubs and occasionally trees. These nests expand over the course of the summer and by the end of the growing season can commonly contain thousands of workers. The workers switch from looking for protein to looking for more sugary materials. This means fruit, pop, fruit juices, and frozen treats. These workers and the original queen will all die when winter sets in though. Only new queens produced by the original will go into the next season to produce the next round of nests. The switch in diet and need to protect the new queens can mean more encounters with humans and an increased defensive nature when nests are discovered.
There are several paper wasp species that can be encountered. They tend to be 1/2 to 3/4 inch long and have smoky-colored wings that you can’t quite see through. Some species are brownish, others red, with some being black and yellow. One of the more common species, the European paper wasp, has coloration that looks very similar to a yellowjacket except their antennae are orange at the tips.
Paper wasps get their name for building umbrella-shaped nests that are constructed out of paper they make by chewing wood scrapings into a pulp. These nests are often found on trees, shrubs, eaves of homes, rafters, railings, and other semi-protected areas. Paper wasp nests don’t get as large as other stinging pests and as a group they tend to be less defensive of the nest than things like yellowjackets. They will sting though, and it can be quite painful. The nest is annual and the insects will die out by fall, with new queens produced overwintering to found their own nest the next season.
This species is the one that has been most confused for the Asian giant hornet. They are also a non-native species, but are slightly less famous than their larger cousins from Asia. Workers of this species are around an inch long, with queens reaching 1 1/2 inches in length. They have a pattern on their abdomen that resembles a yellowjacket’s and is also black and yellow. Their thorax and head are a mix of yellow with patches of dark red, which helps to differentiate them from the Asian giant hornet as well.
They build large paper nests that they will defend by stinging. These large insects are predators; they will consume almost anything they can catch and will eat honey bees (though not quite as aggressively as the Asian giant hornet). They are also known to steal prey from spider webs to eat for themselves. One other interesting feeding habit they demonstrate, in the fall, the workers will girdle tree branches and small trunks and then drink up the sugary material that leaks out.
Management of Stinging Insects
If folks are dealing with a nest of stinging insects, they should consider contacting a professional to help them eliminate the problem. Of course, that might not be feasible for some, so it is important to note the ways that these pests can controlled by homeowners on their own.
First and foremost, they will need to discover the entrance to the nest. Treating individual workers will not eliminate the problem.
Once the nest or entrance has been discovered, an aerosol wasp and hornet product (examples include Raid and Spectracide Wasp and Hornet) can be applied into and onto the nest. These are quick acting products, often needing just seconds to eliminate the nest. The application should be done at dusk or after dark to maximize control and minimize the chances of being stung. The person making the application should also have an escape route planned in advance and a place of safety to retreat to, just in case.
By Jonathan L. Larson, Entomology Extension Specialist
Home gardeners are busy harvesting their crops until the summer garden pests move in! To talk to an expert, I called up UK Extension Entomologist Dr. Jonathan Larson to see what information he could provide to keep these summer pests under control.
A popular summer pest in the Kentucky garden is the Japanese beetle. Japanese beetles are easily recognized by their attractive, shiny emerald-green and copper color. They are about 7/16 of an inch long, and if you look closely, you’ll see patches of white hair on their sides.
The beetles have sharp, chewing mouth parts that allow them to grind up tender leaf tissue between the veins, leaving the leaves skeletonized and lacy. But they don’t stop at leaves. They will shred flowers – you’ve probably seen them buried into the blooms on your roses – and even eat fruit. They attack and feed on more than 300 different plant species. Their favorites include linden, roses, grapes, blackberries and peaches.
So how do you protect your garden from Japanese beetles? First, if you’re in the process of planning or planting your landscape, consider including species and cultivars they don’t like to eat. Examples of those are most oaks, hollies, tulip trees and silver maples.
For those of us whose landscapes are mature and planting more trees isn’t feasible, one of the best methods is to simply pick off and kill beetles when you see them on your plants. Beetles will be strongly attracted to a plant that is already damaged by beetles. The more damage, the more beetles, resulting in more damage and more beetles. It’s a vicious cycle. If you walk through your garden in the evening and remove beetles by hand, you’ll cut back on the number of beetles that show up the next day. Pick them off and plop them in a bucket of soapy water.
There are insecticides available that can help kill or repel beetles, but always follow the label instructions carefully and beware of treating any plant that is blooming. Organic options, which offer a three to four days of protection, include Neem oil, pyola and BtG (Bt for beetles). Synthetic options, which offer protection for one to three weeks, include bifenthryn, carbaryl, cyfluthrin and lamda-cyhalothrin.
Another common summer garden pest is the squash vine borer. The squash vine borer is a key pest of squash, gourds, and pumpkins in Kentucky. Symptoms appear in mid-summer when a long runner or an entire plant wilts suddenly. Infested vines usually die beyond the point of attack. Sawdust-like frass near the base of the plant is the best evidence of squash vine borer activity. Careful examination will uncover yellow-brown excrement pushed out through holes in the side of the stem at the point of wilting. If the stem is split open, one to several borers are usually present. The caterpillars reach a length of 1 inch and has a brown head and a cream-colored body.
Monitor plants weekly from mid-June through August for initial signs of the borer’s frass at entrance holes in the stems. Very early signs of larval feeding indicate that other eggs will be hatching soon.
Home gardeners may have some success with deworming the vines. At the first signs of the sawdust-like frass, vines are slit lengthwise near where the damage is found and the borers removed. The stems should be immediately covered with earth. Sanitation is also important. After harvest is complete, vines should be removed from the garden and composted to prevent the remaining borers from completing larval development.
Gardeners should also be concerned with ticks that can harm the body. To hear the full interview with Dr. Larson, make sure to check out Episode 9 on Summer Garden Pests from the Sunshine Gardening Podcast!
We appreciate Dr. Jonathan Larson being our guest on the show! If you would like to learn more about insects, Dr. Larson also has his very own podcast called Arthro-Pod. To hear more about what is covered on the Arthro-Pod, click here: http://arthro-pod.blogspot.com/.
As always, gardeners keep on digging into gardening and remember to add a little sunshine!
Kristin G. Hildabrand, Warren County Extension Agent for Horticulture