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Our Plants Will Survive "Cicadamania"

Read the story below or click here to see it in full as it was published on Penn Live's website.

Published: May 17, 2013

Fear not, gardeners.

Your flowers, your tomatoes, and yes, even your trees, shrubs and fruit bushes will survive the coming mass emergence of 17-year cicadas.

Despite the hype of "cicadamania," this is one bug that looks – and sounds – a lot worse than it really is.

"Cicadas are not considered pests of our garden plants," says Gregory Hoover, senior Extension associate in Penn State University's College of Agricultural Sciences. "Most gardeners probably won't have an encounter with cicadas since they're usually associated with forests and other wooded areas."

Not only that, but this particular family – known as Brood II – doesn't even venture west of the Susquehanna River.

So you West Shore and Carlisle folks are off the hook just based on geography.

For unassuming gardeners in Dauphin, Lancaster, Lebanon, Schuylkill and 14 other counties to the east and northeast of Harrisburg, the sudden arrival of millions of inch-and-a-half-long, orange-eyed, screeching bugs will seem like the end of gardening as we know it.

No wonder Pennsylvania's early settlers thought it was Round 2 of the Bible's locust plague.

But these periodical cicadas (not locusts at all) don't even have chewing mouthparts.

They don't munch leaves like Japanese beetles, they don't girdle bark like rodents, and even a gazillion of them wouldn't cause the landscape mayhem of a band of hungry deer.

Neither do they sting or pose a threat to gardeners, other than possibly crashing into our foreheads while mistaking us for a hickory trunk.

The main threat to the plant world is the egg-laying activity of females.

About 10 days after the screeching starts, adult females begin cutting small slits in tree and shrub branches with a handy-dandy, saw-like appendage on her abdomen. She'll then deposit a couple of dozen eggs in two rows, then move onto another section or branch until some 400 to 600 eggs are in place.

Mrs. Periodical Cicada especially likes young branches about one-quarter to one-half inch in diameter.

There's some disagreement over exactly how many plant species she'll lay eggs in. I've seen numbers ranging from 80 to 270.

Just about everybody agrees, though, that cicadas favor deciduous woody species as opposed to flowers, vegetables and even conifers (pines, spruce, firs, etc.)

This native bug – the longest-living insect in North America – seems to especially like laying eggs in apple, peach, pear and hickory.

Maple, oak, willow, beech, ash, dogwood, hawthorn and magnolia also make most lists.

Less common but possible is egg-laying on such landscape species as raspberry, rose of sharon, grape, holly, spirea, rhododendron, viburnum and, of course, roses, which most of nature seems to conspire against.

Given enough slits, branch tips may wilt and die.

Otherwise healthy and mature trees will slough off that kind of primarily cosmetic injury as little more than a mild pruning.

However, young trees and shrubs that are less than 4 years old are more at risk since a similar level of damage means loss of a greater percentage of their overall tissue.

Yields from fruit and nut trees also are likely to be less from the lost fruit-producing wood, although those often rebound the following season with a heavier-than-usual output.

Hoover says that if you're concerned about any young trees and shrubs in the yard, wrap them with a covering such as cheesecloth or netting with a mesh that has quarter-inch or less openings.

"People need to tie that off at the bottom because females will crawl up the trunk and gain access to twigs if the cover isn't tied," he says.

He adds that you might also delay planting new woody species until after the cicadafest. The adults should be gone by early to mid-July.

The Davey Tree Expert Co. says it might also be wise to hold off pruning until you see what damage the cicadas have done. You may end up cutting off wood you would've cut off anyway.

Don't panic if you see cicadas on flowers and vegetables. Most likely they're taking a break or on their way up into a tree, not pondering sucking the life out of your lilies.

If you can overlook the swarming numbers and the paranormal racket of the males' mating songs, periodical cicadas actually perform some beneficial services.

For one thing, all of the half-inch exit holes do a wonderful job of aerating the soil and opening rain-catching pockets.

For another, millions of protein-rich bugs offer a tasty treat to birds, fish and eat-anything humans. Cicada recipes abound online.

Most beneficial is the nutrition that all of those dead cicada bodies and empty nymphal skins add to the soil as they drop and decay.

About 6 to 7 weeks after this year's adults finish their job and die, the eggs will hatch. The offspring then will crawl out of their branch slits and burrow into the ground, where they'll spend the next 17 years developing.

Rather than hibernate, cicada nymphs spend those 17 years sucking sap out of tree roots.

Most experts say that damage is inconsequential, although one study from the University of California at Davis claims this slow but steady feeding drain can reduce tree growth by as much as 30 percent – at least when it comes to oaks.

Not much we can do about that anyway.

If you need to worry about something, mark your calendar for 2021.

That's when the much bigger and more widespread Brood X – the one we all freaked out about in 2004 – makes its next return.

And then comes another big one in 2025 – Brood XIV, which mainly affects counties west of the Susquehanna as opposed to this east-of-river clan.

We'll next see this year's buggers in 2030.

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