To kill or not to kill lanternflies?
Penn State Extension has a new rundown aimed at helping gardeners decide if, when, and how to deal with the new spotted lanternfly bug that’s now in all counties surrounding Harrisburg (and 26 counties throughout Pennsylvania altogether).
The bug is currently in the final leg of its nymph stage (red and black crawlers with white spots). That’s the last step before morphing into the more noticeable inch-long gray adults with the distinctive set of orange-red spotted wings when the wings are fully open.
Adults then fly to feed on some 70 different plant species through October.
Penn State says several factors play into what you decide to do if you see spotted lanternflies (SLF) on your property.
A big one is just how many there are.
“A few SLF feeding on a healthy tree is probably not a big concern for the long-term health of that tree,” Extension’s report says. “Nymphs ingest less volume of tree sap than the adults, so a population of nymphs is thought to be less damaging than the same number of adults.”
Large clusters of adults feeding on a new, stressed, or particularly favorite tree – dubbed a “hot” tree – is a different story. Then treatment is more warranted to prevent dieback or even loss of the targeted plants.
Researchers are finding that lanternflies have a few favorite plants and that their preferences change as the season progresses.
Lanternflies really like grapes and the weedy tree-of-Heaven all season long (nymphs and adults both), while roses and walnut trees are additional favorites in May and June.
This month, they lean toward grapes, trees-of-Heaven, and walnut, birch, willow, and sumac trees.
From August through fall, the adults aren’t as keen on walnuts, but they still like grapes, trees-of-Heaven, birch, willow, and sumac trees, plus silver and red maples.
Part of each home owner’s decision will involve how many SLF favorites they have in the yard and how tolerant they are of damage.
Penn State adds: “To date, we have not observed SLF killing otherwise healthy ornamental trees in landscapes. We have only observed SLF killing trees-of-Heaven, grapevines, and small tree seedlings. Also, large numbers of SLF nymphs feeding have caused wilting on herbaceous plants (perennial and annuals) and branch dieback on some trees.”
Tolerance also comes into play with a side effect of SLFs – black coatings of a substance called sooty mold that forms on surfaces where partly digested SLF waste material (“honeydew”) has fallen.
Penn State says sooty mold often “grows under heavily infested trees and can result in cosmetic damage to decks, cars, and other possessions.”
Although lanternflies themselves don’t sting, their honeydew can attract bees, wasps, and other insects that do. Not all homeowners are OK with that, even if SLFs aren’t harming plants with their feeding.
If you decide to take action, Penn State suggests starting with the least toxic options – scraping away lanternfly eggs and trapping the crawling nymphs.
Lanternflies lay egg clusters that look like mud smears on tree trunks as well as all sorts of surfaces, including wood, rocks, tires, glass, and even lawn furniture.
Scraping the clusters into a plastic bag of rubbing alcohol or hand sanitizer will kill the eggs, as will smashing them. Penn State Extension has an online video that shows how to do both.
November through April are the prime months to watch for and kill eggs.
Since nymphs crawl up trees and often move from tree to tree, strapping sticky bands on tree trunks is an effective way to trap and kill them without chemicals. Traps are especially effective in May, June, and July.
Penn State Extension has an online video on how to sticky-band a tree.
To kill adults, Penn State says options include insecticides that kill the flying bugs on contact and chemicals that are taken in by plant roots or trunks and distributed throughout leaves and other plant parts (“systemic” insecticides).
“Spotted lanternfly nymphs and adults are both fairly easy to kill with insecticides,” says Penn State’s report. “Even the less toxic insecticides like soaps and oils can work well.”
Several widely available chemical insecticides kill adults with varying lengths of effectiveness (“residual action”), including bifenthrin, beta cyfluthrin, carbaryl, malathion, and pyrethrins.
Dinotefuran and imidacloprid are two systemic controls that can be applied in summer.
Penn State Extension has a web page with more details on control options, including lanternfly photos and a chart on the pros and cons of each control.
Extension does not recommend any of the home remedies that gardeners might hear about, pointing out that just because they’re common in homes doesn’t mean they’re “safe.”
Dish detergent, for example, can burn plant leaves, hot pepper sauce or vinegar can do serious eye damage, and cooking a homemade bug brew can create vapors that are harmful to lungs, eyes, and skin.
If you’re outside one of the 26 quarantined counties and spot a lanternfly, report it to the SLF hotline at 888-422-3359 or send a report through Extension’s lanternfly web page.
Cut flowers first thing in the morning to use them in vases.
The best flowers for cutting
A side benefit of growing flowers in the yard is that it gives you ready access to the freshest cut flowers you’ll get anywhere – cheaper than buying retail, too.
Plant enough annuals and perennials, and you should have a nice bouquet selection from tulip and daffodil time in spring to the last asters, mums, and goldenrods of fall.
Your annuals should be hitting peak bloom this month, giving you plenty of snippable choices now and for weeks to come.
Some of the best cut-flower annuals include cosmos, zinnia, dahlia, sunflower, gladiolus, ageratum, angelonia, celosia, gomphrena, and if they’re still blooming, larkspur and osteospermum (cape daisies).
Lots of perennials bloom this month and into August, too. Some of the best mid-summer choices for cutting include lily, coneflower, perennial sunflowers, black-eyed susan, liatris, yarrow, stokesia, phlox, betony, veronica, baby’s breath, astilbe, verbascum, and penstemon.
Besides spring bulbs, other good early-season cut perennials include peony, poppy, dianthus, salvia, and shasta daisy.
Roses, lilacs, and hydrangeas are three of the best cut-flower shrubs.
Fresh-use flowers are best cut just as they’re opening early in the morning or at dusk.
Flowers for drying are best cut around midday and chosen at peak bloom. Most flowers air-dry, but some dry best in silica gel and/or borax and sand.
Keep cutting your fresh flowers as long as they keep coming. It doesn’t weaken or harm the plants.
The only down side – if it is one – is that your outdoor display won’t look as full if you cut a lot of flowers to take inside or give away.
Mitigate that by cutting from the least-seen sides or taking just a few from multiple plants instead of a lot from any one.
Six tips on maximizing vase life:
1.) Cut flowers in early morning or at dusk when the air is cool. Take a container of tepid water into the garden with you.
2.) Select flowers in the late bud stage and just about to open instead of ones that are fully open.
3.) Use sharp pruners or scissors to make a clean cut. Cut the stem longer than you need for the intended vase.
4.) Immediately immerse the cut stem in the container of water.
5.) Once inside, mix floral preservative in tepid water and fill your display vase about three-quarters full. Make a fresh cut immediately before placing each of the cut flowers in the vase.
6.) Change the water with new preservative every two or three days. Make fresh cuts to the stems before putting them in the replaced water.
Stop for drink breaks in the garden so you don't get dehydrated in this hot weather.
Drink, gardener, drink!
We’re into a hot, dry spell now, which means prime time for dehydration if you’re not drinking enough while out there gardening.
Dehydration is an underrated health risk, more so as we age. Gardeners are also more prone to it than air-conditioned couch potatoes and other heat avoiders.
Common early symptoms include a headache and muscle cramps, eventually leading into dizziness, rapid heartbeat, rapid breathing, loss of energy, and possibly fainting.
This one’s an easy one to head off… drink plenty, even if you don’t feel thirsty. A half-cup of water every 15 minutes is a good guide.
That’s easier said than done because gardeners tend to focus on the job at hand or put off going inside to get a drink because they’re dirty.
Solve that by taking a bottle of water outside from the beginning. Keep it handy so you take swigs often.
Whether you’re drinking enough or not, don’t overdo it in really hot weather to the point of risking heat exhaustion or heat stroke.
Pay attention if your body is trying to tell you something, such as getting dizzy or light-headed (a possible sign of low blood sugar) or getting short of breath.
Make sure you’re covering up or using sun screen to guard against skin cancer, and try to keep gloves on as much as possible to prevent cuts and punctures.
Read more on how to stay safe in George’s 2019 article on “How not to hurt yourself in the garden.”
- More when-to-do-what tips: George’s “Pennsylvania Month-by-Month Gardening” book