Protecting your trees and shrubs from summer insects comes down to three things: keep them healthy so they can resist pests, know which Kansas insects to watch for and when, and treat the right pest at the right moment. Two of those moments are happening right now bagworms need treating while they’re small (late May through June), and valuable ash trees should already be on an emerald ash borer protection plan. The trees in your yard are a major part of your property’s value, and a little timely attention now prevents the kind of damage that’s expensive or impossible to undo.
Here’s the Johnson County insect lineup, how to protect against each, and the two priorities that can’t wait this summer.
What bugs attack trees and shrubs in Kansas?
A handful of insects cause most of the tree and shrub damage in our area:
- Bagworms the top threat to evergreens like junipers, arborvitae, and spruce. They build spindle-shaped “bags” from the foliage they eat, camouflage beautifully, and a heavy infestation can defoliate and kill a shrub. They must be treated while small.
- Emerald ash borer (EAB) now established throughout Johnson County, which is under quarantine. This metallic-green beetle kills ash trees: larvae tunnel S-shaped galleries under the bark that cut off the tree’s water and nutrients. Untreated ash trees in our area will eventually die.
- Japanese beetles shiny metallic-green beetles that appear in late June and skeletonize leaves on roses, lindens, birches, and fruit trees, turning foliage to lace. Their larvae are the same white grubs that damage lawns.
- Borers several species that attack stressed or weakened trees, tunneling under the bark; healthy, well-watered trees are far less vulnerable.
- Scale insects euonymus, magnolia, and pine scale attach to stems and needles, suck sap, and leave sticky honeydew and black sooty mold.
- Aphids and spider mites summer sap-feeders that cause stippling, yellowing, and honeydew, especially on stressed plants in hot, dry weather.
How to protect your trees from insects in summer
Effective protection is a layered approach, not a single spray:
1. Keep them healthy
A vigorous tree resists insects far better than a stressed one borers in particular target weakened trees. Water deeply during summer heat and drought, maintain a proper mulch ring (not piled against the trunk), and prune correctly to remove dead or damaged wood. Our expert bush and shrub trimming, landscape maintenance and professional irrigation services all feed directly into keeping trees strong enough to shrug off pests.
2. Know the timing and monitor
Timing is everything with tree insects. Watch for bagworms in late spring and early summer, Japanese beetles from late June through August, and scale crawlers and borers in spring. Catching a problem early while the bagworms are small or before beetles concentrate is the difference between a simple treatment and a lost tree.
3. Treat the right pest the right way
Different pests need different treatments: a properly timed spray for bagworms while they’re small, systemic trunk or soil injections to protect ash from EAB, targeted treatment for Japanese beetles during peak feeding, and horticultural oil for scale and mites. Many of these are systemic or injection treatments that require professional application and precise timing to work.
4. Don’t make it worse
Two common mistakes backfire. Japanese beetle pheromone traps actually attract more beetles to your yard if you use them at all, place them far from the plants you want to protect, or skip them entirely. And cutting bagworm bags off and tossing them nearby just relocates the eggs; bags removed by hand in winter need to be destroyed.
Two summer priorities that can’t wait
If you do nothing else this summer, handle these two. First, bagworms: the treatment window is open now, while the larvae are small and vulnerable wait too long and the bags harden and treatment becomes far less effective. Second, ash trees: if you have a valuable ash, it needs to be on an EAB protection program, because in a quarantined county like ours, an untreated ash is on borrowed time. Japanese beetles are tied to lawn grubs as well, so if you’re seeing beetles, it’s worth checking your turf and considering grub control too.
Why professional treatment matters here
Tree and shrub insect control isn’t always a DIY job. Correctly identifying the pest, choosing the right product, and applying it at the precise window often via trunk or soil injection is where professional treatment earns its keep, especially for high-value trees. A misdiagnosis or mistimed spray wastes money and lets the pest win. Combining targeted treatment with our lawn pest control gives your whole landscape coordinated protection.
Tree and shrub protection across Johnson County
MW Lawn & Landscape protects trees and shrubs for homeowners in Olathe, Overland Park, and throughout Johnson County with treatments timed to our local pest cycles, from bagworms to ash borers. As a family-owned company for 25+ years, we know which pests show up here and exactly when to act.
Worried about bagworms, beetles, or a struggling ash tree? Request a free quote or call (913) 829-4949 the sooner we look, the more of your landscape we can protect.
FAQs
How do I protect my trees from insects in summer?
Keep trees healthy so they resist pests (deep watering, proper mulch, correct pruning), monitor for the pests active in each season, and treat the right pest at the right time a timely spray for bagworms, systemic injections to protect ash from emerald ash borer, and targeted treatment for Japanese beetles during peak feeding. Many treatments are systemic and best applied by a professional.
What bugs attack trees in Kansas?
The most damaging in our area are bagworms (on evergreens like junipers and spruce), emerald ash borer (which kills ash trees), and Japanese beetles (which skeletonize leaves on roses, lindens, and birches). Borers, scale insects, aphids, and spider mites are also common, especially on stressed plants.
When should I treat for bagworms in Kansas?
Late May through mid-to-late June, while the larvae are still small. Once the bags grow larger and harden, treatment becomes much less effective, so the early-summer window is critical for protecting junipers, arborvitae, spruce, and other evergreens.
Should I treat my ash tree for emerald ash borer?
If it’s a valuable, healthy ash and you want to keep it, yes. Emerald ash borer is established throughout Johnson County, and untreated ash trees in the area will eventually die. Johnson County K-State Extension recommends spring treatments before adult beetles emerge. Treatment is usually a systemic injection best done by a professional.
Do Japanese beetle traps work?
Not the way most people hope. Pheromone traps actually attract more beetles to your yard than they catch, so they can make damage worse. If you use them, place them far from the plants you want to protect. Targeted treatment during peak feeding is more effective, and because the larvae are lawn grubs, grub control helps reduce next year’s population.
How do I know if my trees have an insect problem?
Watch for skeletonized or chewed leaves, spindle-shaped bags on evergreens, sticky honeydew or black sooty mold, stippled or yellowing foliage, small exit holes in bark, and branch dieback. Catching these signs early gives you far more treatment options than waiting until the damage is severe.