Aphid Honeydew Can Cause Damage
Do you have a problem with aphids?
Quick checklist of aphid symptoms:
- Honeydew on car, deck or lawn furniture
- Little green, white or woolly insects on the underside of leaves
- Leaves drying out, wrinkling or dropping off early
- Lots of little bugs on the tree
- Lots of ants or some wasps around the tree
- Problem always happens in early Summer, May – June
If you’ve noticed a greenish-yellow residue on your plants or yard around late May or early June, you may have wondered where it comes from. Aphid “honeydew” is a substance excreted by aphids in late spring, and found on tree and plant leaves, as well as surfaces below trees and plants.
You may have tried to wash off your car, BBQ or deck and find that it is very hard to remove this stuff. In fact, aphid honeydew or spitting can cause permanent damage and discolouration. Sometimes it is only a little bit and can be scrubbed away, but if you have an aphid infestation you may be desperate to get rid of these creatures.
We understand. We’re Certified Arborists in Toronto who would be happy to help you with your aphid problem!
What causes honeydew?
The sticky substance is what aphids excrete after eating plants and other bio-matter. Since trees and tree leaves have water (or sap) running through them, when the aphids are feasting they are taking in a lot of water and starchy nutrients, and then leaving droppings across your property.
It’s not quite as gross as it sounds: aphids’ diet is entirely plant sap, so the substance you may find on your leaves, deck, barbecue, or car isn’t much different from regular sap. Certain species of ash, beech, cedar, chestnut, elm, fir, hickory, maple, oak, pine, poplar, spruce, and willow trees produce sap that feeds aphids. A few other plants, including currants, grapes, and sunflowers, also produce this sap.
Other problems caused by honeydew: Ants or Wasps
Ants love honeydew. They are so keen on it that sometimes, ant colonies will actually work together with the aphids by “farming” them so they produce more honeydew for the ants to eat. This symbiotic relationship is pretty cool – except if it means your car or deck is getting destroyed.
Wasps also love honeydew, though they are less of a problem than ants. Wasps and ants both like the sugars in honeydew, but due to the timing of aphids, wasps usually are less of an issue as their lifecycle isn’t in full swing at the same time. Since aphids come early in the summer and wasps tend to be problematic mid to late summer, its usually less of an issue. But if you have a number of wasps around, honeydew could be the issue.
What type of trees do aphids eat?
Aphids can attack many different types of trees found in Toronto. Most often we find them in Honey Locust trees because they are so common, making it easy for the pest to spread. But there are many different varieites of aphids, and many of them attack a wide range of trees including maple trees, beech, cedar, oak, spruce willow, Japanese Maples, American Elm trees, Horse Chesnut and more.
To get rid of aphid honeydew, you’ll need to get rid of the aphids. Fortunately, there are many effective treatments to remove aphids on plants. For trees, certified arborists and plant healthcare workers in Ontario can offer effective professional insecticidal treatments for your trees. Some other treatments can supplement these and be done either by a professional, or by homeowners and residents.
Aphids in Ontario
When are aphids active?
Southern Ontario’s aphids tend to appear in late spring each year, usually late May to early or mid-June, and they stick around all summer.
Common Aphids in Toronto
Green peach aphids and potato aphids are the most common aphid types in Southern Ontario, both small and yellow-green in colour. You’ll commonly find them on the undersides of leaves.
Woolly Aphids
Woolly aphids have a very different appearance. If you’ve noticed something that looks like bits of cotton or white mould along branches, twigs or leaves of trees, you may have a woolly aphid problem. These hairy insects are covered in white fuzz.
Where they Live
This species is particularly fond of columnar beech trees or beech hedges. Wherever these hedges are extremely popular, there you will find numerous infestations on close to every block. In areas such as Rosedale, Bedford Park, Forest Hill, Moore Park, Lawrence Park, Davisville, York Mills and other North York and Central Toronto neighbourhoods these pests are endemic.
This means that ongoing treatment is required, because there are so many “homes” for them to live in due to the popularity of beech hedges, they cannot be entirely removed from any property.
Black, Sooty Fungus from Wooly Aphids
Honeydew from woolly aphids can also cause into a black fungus that looks like soot. This fungus is unattractive, and if it spreads widely over a tree, it can start to block sunlight from getting to the trunk and branches. As the sunlight is blocked, the tree can’t generate enough energy from photosynthesis and so begins to suffer or die.
Woolly aphids common to elms and other trees can be much harder to treat because they don’t stay on the trees they attack over the winter. Instead, they “over-winter” on other trees nearby and only come back in the spring. Due to the size of the trees prone to this, systemic pesticides are generally chosen for treatments
Getting Rid of Aphids and Honeydew
A certified arborist or pest management professional can offer an insecticidal treatment to your trees to control a large aphid infestation. In Ontario, insecticidal treatments like this can only be administered by licensed professionals.
Licensed Aphid Extermination: Systemic Insecticides
Vista Tree offers aphid treatment with ACECAPS (manufacturer product pdf), a systemic insecticide inserted into a tree by drilling a hole then hammering in a cap of the insecticide. This treatment should be done in springtime, when leaves on trees have come out and before an infestation is in full peak during the summer months.
Ideal Treatment for Large Trees but not Fruit Trees
This treatment is ideal for aphid honeydew in large trees, where spraying the full tree is impractical or impossible. The caps are placed at intervals through the tree and the insecticide will work itself through the interior of the tree, killing aphids and several other destructive insects.
Protection lasts for between 12 and 18 weeks, depending on the scale of the infestation.
ACECAPS are not suitable for fruit trees or any trees where nuts or sap are consumed. ACECAPS are regulated pesticides, and injection of these caps is permanent.
Controlling Aphids – Ontario Law
Due to the potential for (minimal) damage to the tree, and the ecological considerations of using pesticide, a Certified Arborist with an Exterminator License will inspect your tree before prescribing this treatment.
According to Ontario Pesticide regulations, the goal of any pest treatment is not eradication but control. Since aphids are widely present in the environment, they cannot be permanently removed from your tree. Any treatment provided by any company will only last for the year, and need to be reapplied in subsequent years if the cause of the infestation is not addressed.
There are a lot of good reasons to try to avoid pesticides as much as possible.
Why Aphids Attack Trees and What to Do
Generally speaking, tree pests prey on trees that are vulnerable due to stress. This might mean your tree is suffering from lack of water, competition with other trees, lack of nutrients in the soil, recent damage from a storm, another pest infestation or some other issue. When trees are weakened, their “immune systems” become more vulnerable just like people.
So while we can suppress a pest infestation with pesticides, it will not address the underlying reason the tree was vulnerable. This is why it is critical to consider the whole tree, its overall health, your goals for treatment and budget.
Ongoing pesticide treatments are not environmentally friendly in most cases, have to be repeated and are costly. Educating yourself about your particular tree and understanding how Integrated Pest Management works is key to controlling pests, keeping trees healthy and saving money.
Eco-friendly Aphid Treatment: Ladybugs or Aphidoletes
One alternative to pesticide application is the use of other bugs! Aphidoletes and Lady Bugs are beneficial insects that will eat aphids, and can be used to naturally control aphid infestations. Brown Lacewing and Anystis can also be used.
Word of caution: Aphidoletes, Brown lacewing and Anystis are bugs in the sense that many people will find it challenging to take care of and release them, or be grossed out by them. For this reason, we recommend Lady Bugs to homeowners who aren’t excited about the prospect of bringing insects into their homes.
You can order ladybugs online and release them into your garden where they will create baby ladybugs (called nymphs) that can eat thousands of aphids a day. This is quite cost effective, but may be challenging to administer if your tree is very large. This treatment works best either on smaller trees like Beech trees with woolly aphid, or if you can use a ladder or a climbing arborist to place the ladybugs in a larger tree.
Where to buy Predatory Bugs
Boxes of hundreds or thousands of dormant ladybugs can be purchased from some reputable online retailers, some garden centres and big box (Costco does shipping!) or hardware stores in the summer each year, normally through late June in the GTA and Southern Ontario, though the exact shipping dates will vary based on the weather forecast. If it’s too hot, over 30°C, you should wait for cooler weather.
- Recommended Independent Canadian Retailers*: The Bug Lady and The Dragon Lair
- Also sold by: Costco – Ladybugs
*We do not receive any benefit, incentive or compensation for recommendations. All of our recommendations are independent and based on the personal opinions of Certified Arborists on staff at Vista Tree. YMMV
How to Care for and Release Lady Bugs
Ladybugs are kept in the fridge until you’re ready to release them.You should release ladybugs at dusk or in the early evening, as they will fly away in the heat of the daytime. Release them into a garden bed, watering the area first. Spacing out the release of a package over a few days will give the best results.
Environmental Impact
A thing to note about ladybugs: everything comes from somewhere and ladybugs are no different. Depending on where you buy them, they may be cultivated or they may be wild caught. Cultivated bugs are better for the environment as wild caught specimens can deplete populations in the areas they are caught, leading to ecological issues.
It’s OK to take the easy route and source lady bugs from wherever you can get them, but if you have the time and opportunity, a little bit of research is a good idea.
Other Eco-Friendly Treatments: Insecticidal Soap and Prevention for Next Season
Insecticidal soap, such as Safer’s Insecticidal Soap, is a safe product for treatment on plants (including edible plants like cucumbers and tomatoes). Safer’s and similar products are made from potassium salts and safe for the general public to use. They contain no synthetic chemicals and work as a contact poison on soft-bodied insects like aphids.
Safer’s Insecticidal Soap can be used alone or in combination with ACECAPS, but you should not use it if you are releasing ladybugs as it can harm them. Safer’s is a great DIY alternative to pesticides or ladybugs.
To supplement a treatment like ACECAPS, you can spray insecticidal soap regularly on your plants through the summer, making sure you coat both the top and bottom of leaves. Avoid spraying in very hot weather over 32°C.
Regular use of organic fertilizer in your garden also helps to control nitrogen levels, which will help keep aphids out.
How to Clean up Honeydew
Since aphid honeydew is essentially just sugar from trees, you can use warm water, soap and vinegar to wash off honeydew. For extremely resistant stains like on wood or patio stones, you may want to use a pressure washer without chemicals to remove the build up.
Lastly, you can also use sap removing agents used by Certified Arborists to clean tools and ropes like Sap Zappper. Since sap is roughly the same as honeydew, these products should break down tough to remove honeydew stains. We have used this product ourselves for this purpose and found it effective.
The link above goes to a Canadian store for professional arborists where you can purchase it yourself. We do not receive any benefit or incentive from this product or the store – it’s just our personal experience talking. Just make sure to test any products on a small area before you use them to ensure no damage will be caused.
Conclusion: Fixing Aphid Honeydew Problems
In this post we covered a lot of info about aphids and honeydew problems in Toronto. You learned about where aphids come from, what honeydew is and three different ways to treat aphid infestations.
We also discussed why aphids attack trees, which is very important to understand so you can keep your trees healthy and safe. Treating a pest infestation is not a cure-all solution, to limit pesticides and pest problems on your property it is more effective to take care of the total health of your trees so they can naturally fight off infestations.
It’s the right time of year to be thinking about aphid treatments for your trees! For assistance with aphid removal and insecticide treatment, contact Vista Tree to find out about your treatment options.
Please contact me to let me know if there is a solution for this problem and how much your charge.
Hi Fred,
We will send you an email today about this! We can certainly help you out.