Identifying Common Spring and Summer Tree Insects (Pests)

Identifying Common Spring and Summer Tree Insects (Pests)

We’re weeks into the growing season, and our trees are happy to show off their fresh appearance: a full, blooming canopy, sprouting flowers and fruits and—wait, are those curling leaves?

Damage to tree leaves and stems is often the first sign of a bigger tree problem, possibly an insect infestation.

If you’ve seen something odd on your tree, find out what the problem is. Use our checklist below to pinpoint what insect could be damaging your trees and how to stop it.

Symptoms: Leaf curling, twig dieback, a sugary substance called “honeydew,” black, sooty mold and stunted growth

  • What insect is damaging my tree: Aphids, the resident “plant lice”

  • What do aphids do: They feed on tree leaves and stems, prevent proper nutrient and sunlight intake and cause premature leaf drop.

  • How to control aphids on trees: Stop aphids using horticultural soap treatments or insecticides.

  • When to control aphids: Talk to your arborist as soon as you spot symptoms.

Symptoms: Chewed, ragged-looking leaves that fall prematurely in spring 

  • What insect is damaging my tree: Cankerworms, the hungry, hungry caterpillar

  • What do cankerworms do: They eat away at leaves, stripping the tree of nutrients.

  • Most common tree victims of cankerworms: Elm, oak, apple, maple, linden, beech, cherry, hickory and ash

  • How to control cankerworms: Apply a pesticide in spring to remove cankerworms. Then prevent in the fall with an insecticidal tree band.

  • When to treat cankerworms: Control this pest in spring and focus on cankerworm prevention in fall.

Symptoms: Chunks of leaves chewed down to the veins, browning leaves around the top of the tree canopy and leaves falling in summer

  • What insect is damaging my tree: The flying, feeding Japanese beetle

  • What do Japanese beetles do: They feed on tree leaves in warm, sunny weather. This tree pest often eats the entire leaf, leaving behind only the skeleton.

  • Most common tree victims of Japanese beetles: Crape myrtle, birch, littleleaf linden, crabapple, purple leaf plum, Japanese maple and Norway maple

  • How to control Japanese beetles: Apply one or two pesticide treatments a few weeks apart.

  • When to treat for Japanese beetles: Act during peak growing season, from mid-June through August.

Symptoms: Large, silky spider webs and tree leaf loss, especially on black cherry trees

  • What insect is damaging my tree: The extremely troublesome Eastern tent caterpillar

  • What do Eastern tent caterpillars do: They chew on foliage, leave behind webs and create an unsightly appearance. On black cherry trees, this pest is a serious threat.

  • Most common tree victims of Eastern tent caterpillars: Black cherry, ash, birch, sweetgum, willow, maple and oak

  • How to control Eastern tent caterpillars: Clip and destroy the tents.

  • When to get rid of tent worms: Wait until winter to remove the silky webs. Your arborist can also apply a treatment to control the larvae.

Symptoms: Yellow spots or leaf curling on new tree leaves, premature leaf drop, a clear, sugary substance on or under your trees, black fungus and lots of ants

  • What insect is damaging my tree: The un-welcomed whitefly

  • What it does: Whiteflies suck plant sap from new, tender tree leaves.

  • How to control whiteflies: You can get rid of whiteflies by using horticultural oil treatment or yellow sticky traps.

  • When to apply whitefly treatment: Whiteflies pose no immediate threat and may be controlled by other predatory insects.

Symptoms: Silky “webs” in trees, chewed leaves, mild to severe leaf loss and branch death with no regrowth on evergreens

  • What insect is damaging my tree: Bagworms, the camouflaged critters

  • What do bagworms do: Bagworms consume tree leaves, often unnoticeably, until severe damage occurs.

  • Most common tree victims of bagworms: Juniper, arborvitae, cedar, spruce, honeylocust, linden, willow, maple, oak, birch, elm and poplar

  • How to treat bagworms in trees: Begin by handpicking and destroying all bags. If that’s not practical, your local arborist can apply an insecticide treatment.

  • When to control bagworms: Remove bags as soon as you spot an infestation.

See any of the above tree pest signs? Ask your local arborist to inspect your trees – for free.

  • The Tree Doctor November 5, 2018 >Hi Rita, I forwarded your request to your local office. They will reach out to you as soon as they can to schedule a free consultation. You can also reach them directly at (630) 352-0569. Here if you need any more assistance, Rita.
  • The Tree Doctor November 5, 2018 >Hi K, Bark splits can be caused by several factors. Physical stresses on the tree from wind or structural defects as well as canker diseases or other factors can result in the formation of splits. Birches are also subject to foliar diseases that can cause spots or blotches on the foliage. I recommend that you have a certified arborist inspect the tree. They will be able to make an accurate diagnosis on what is causing the splits and prescribe the proper treatment plan, if necessary. Unfortunately, Davey Tree does not service your area based on the zip code provided. Here is a resource that can help you with hiring a certified arborist in your area: Hopefully, this helps. Best of luck to you, K.
  • K B October 27, 2018 >My weeping paper white birch tree had split its bark and noticed some leaves on canopy with dark spots. Please advise. Thank you.
  • Rita Regains October 27, 2018 >My evergreen tree is dying Inspection needed
  • The Tree Doctor August 8, 2018 > Hi Wanda, The ability of a woody plant to releaf following defoliation is primarily dependent on the health of the plant. If the plant is in good health, with adequate stored reserves, the tree should be able to form new buds to replace the lost foliage. However, if reserves are low, it may only be able to regenerate a few leaves over portions of the plant. This can take some time to occur because the plant often must activate dormant buds or create new ones depending on preexisting conditions. While new growth is forming, it will be important to make sure the plant is adequately watered, because the new leaves will be very susceptible to desiccation As for the grasshoppers, I suggest you contact the staff at a nearby garden center for advice. Contact insecticides labeled for fruit trees are available that you can apply to the trees you wish to protect. They should be able to advise as to which material will be most effective for your situation. Hopefully, this has been helpful. Best of luck to you, Wanda.
  • Wanda White August 1, 2018 >Grasshoppers have eaten all of the leaves from my apple, fig, and peach trees., grape vines Now they are starting to eat leaves from my hardwood trees. Will this kill the trees for next year. Also, will the trees bear fruit again? What can I do to stop the grasshoppers from eating all the leaves? thanks
  • The Tree Doctor July 9, 2018 > Hi Vickey, There are several over-the-counter insecticides that will work. I recommend you go to a local garden center and explain to the staff that you want to control caterpillars feeding on your ornamental redbud. They will show you the materials they have on hand and help you make the proper selection based on your needs and preferences. You can also check the Michigan extension website,, for their recommendations. Hopefully, this helps! Here if you have any more question, Vickey.
  • Vickey Weber July 8, 2018 >What spray can I use attach to a hose to kill worms making nests in my small red bud tree. I cannot afford a lot of money to have you guys charge to look at and then treat. I do not want to loose my tree it was a memorial tree to my dec'd father. Just need to know what I can use to spray the tree to kill larvae and I will try to remove nests in winter month. thank you
  • The Tree Doctor May 15, 2018 >Hi Donnell, They may be chewing off small bits of bark that they mix with saliva to make the paper they use for nest construction. This typically doesn’t harm the tree. You can try to spray the trees with an over-the-counter insecticide to discourage them from visiting your trees. Hopefully, this helps! Here if you have any more questions, Donnell.
  • Donnell Flanagan May 14, 2018 >I have several arborvitae in my yard. They are attracting all types of bees. There’s no nest in the area. I see them on them and then they fly away. Is this normal? Is there anything I can do to prevent this?
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