Insect Threats to Ornamentals and Shrubs

Information is a powerful force, and the more information you have regarding the signs and symptoms of pests and diseases, the better off your ornamentals and turf will be. Last month, we wrote about some of the most common diseases that affect the trees in this neck of the woods, things like needlecast, anthracnose and apple scab.

This month, we want to highlight some of the most dangerous insects or pests that enjoy feasting on the grass and trees you’ve planted.

Be Proactive When it Comes to Common Pest Prevention

The best thing you can do when it comes to preventing common pests or threats to your lawn and ornamental trees is to know which ones live here. For example, emerald ash borers are a biggie – so much so that we dedicated an entire blog to these emerald beauties. This is also a good time to read up on grubs and grub control so you can have the luscious lawn you’re fantasizing about this spring, summer and fall.

For this post, we want to focus on three others:

  • Two-Spotted Spider Mites
  • Gypsy Moths
  • Spotted Lanternfly

Get these three little buggers on your radar so you can recognize any signs they may be taking up residence where they’re not wanted. You can also contact us here at Joshua Tree to learn more about our various plant healthcare programs. Once you sign up, your property will turn up on our calendars and we’ll inspect, treat and maintain your trees and/or turf for you.

Two-Spotted Spider Mites

If it’s not grass, the two-spotted spider mite (Tetranychus urticae Koch) probably likes to eat it for breakfast, lunch and dinner. These teeny pests are very smart – their size and the fact that they feed on the under-side of leaves - makes them largely undetectable until they’ve done considerable amounts of damage.

Two-spotted spider mites like to suck the juice out of the foliage on shade trees, shrubs and flowers (like we said, anything that isn’t a lawn…). The females overwinter underneath bark and other groundcover. Once the weather warms up, they mate and begin saying several eggs per day, on the underside of leaves, for a total of about 100 eggs per lifetime. Hot dry weather is the ideal condition for two-spotted spider mites to thrive, and during a year like that, we may see anywhere from 10 to 15 different generations of spider mites cycle through. Whew!

Since these pests suck the fluid from the leaves, the most obvious sign of infestation are leaves that appear pale in color (because they’re lacking chlorophyll), speckled with very small dots and – in severe cases – the foliage will simply drop from the plant or tree.

The only way to prevent and treat them is to identify they are, indeed, the cause (by using a magnifying glass or microscope to identify the mites on the underside of leaves) and then wiping out various lifecycle stages by spraying miticides at regular intervals. These clever pests develop resistance to specific pesticides so we have to change up the chemical composition every few rounds or so to make sure treatments remain effective.

Gypsy Moths

Like most of the pests we spend our lives trying to eradicate, the Gypsy Moth isn’t from ‘round these parts. They were introduced into Massachusetts in 1869 and established themselves throughout New England over the next 50 years. The Gypsy Moth is considered the most important pest of forest and shade trees in the eastern United States.

For the poor infested trees, it’s like a one-two-three punch combination. First, the larval form of the moth devours canopy foliage to prepare itself for the coming metamorphosis into its moth form. When a tree is sufficiently depleted of its foliage, it becomes stressed. In its stressed state, it’s a prime target for secondary pests, like two-lined chestnut borer, Agrilus bilineatus , and shoestring root rot, Armillaria spp. Once these pests are onsite, the tree can’t compete and it dies.

Unfortunately, similar to two-spotted spider mites, the first round of defoliation or damage may be hardly detectable unless you’re really paying attention. By the time defoliation is more noticeable – usually after 31% to 50% of the foliage is lost, the pest problem is more significant – but still treatable. After a year of 51% or more defoliation, hemlock, pine, and spruce will typically die. Deciduous trees can typically stand two or maybe three years of untreated gypsy moth defoliation but mortality rates spike after that point.

While there are some natural predators and diseases help keep gypsy moths under control, registered pesticides are the most effective way to eradicate them. These chemical treatments work best when applied in early spring, after the larva have hatched – during early- to mid-May – before the larva get too large. It’s always best to treat the problem before heavy loss of leaves has occurred.

Spotted Lanternfly

This one’s a new pest on the block. Detected in Pennsylvania only a few years ago, the spotted lanternfly originates from Asia – China, Japan, Vietnam and India. They have piercing-sucking mouthparts and enjoy dining on grapes, apples, stone fruits and pines – and that’s just the beginning. Their favorite host plant is their own, native-to-China, “Tree of Heaven,”Ailanthus altissima. If you have a Tree of Heaven planted, keep a close eye out for any signs of spotted lanternfly activity.

Because the pest is so new, experts are working on quarantining and eradicating new infestations in order to keep it under control. Currently, the spotted lanternfly is detected in several counties, including our own Lehigh County.

Please visit the Pennsylvania Department of Ag’s Spotted Lanternfly page to learn more about how to identify this pest at various stages in its life cycle. They have multiple pictures of what the pest looks like in all of its forms and identifying, reporting and quarantining is especially important in these beginning stages of its residency here in the U.S.

Pesticides are currently the most effective way of killing the spotted lanternfly, but it’s important that you contact a professional or follow the instructions on the PDofAg’s website to report the infestation appropriately.

Need assistance identifying what’s going wrong with your trees, shrubs or lawn this year? Contact us here at Joshua Tree so we can take a look. Early detection and early treatment are the best way to stop harmful pests before their damage goes too far.


Ready to get started?

Request a Free Consultation