I've got honeydew on my honey-do

Posted by: Todd Hagenbuch, Routt County Extension

The Futura will look brighter after a good wash.
(Well, after that and the paint job I'm pushing for...)

My honey-do list this summer is a long one. Of course, I put a lot of it on there myself, but it includes planting new gardens, tending to the lawn, weeding the existing gardens, keeping an eye out for the usual insects, (yes, I’m talking about you, Columbine Sawfly) and more. I even have some non-yard items on my list, one of which is convincing my mom that we need to restore her 1966 Ford Falcon Sports Coupe. That honey-do actually alerted me to an insect issue in my trees. How, you ask?

I took Mom’s car from her home a couple of weeks ago to get some estimates on the work. In the time since, it’s been in my driveway instead of in her garage. When I met her with the car to discuss the restoration, she questioned what had happened to her already-spoiled paint job. “Honey, what did you do?!?” she exclaimed. “This honey didn’t do anything, Mom,” I replied. “That’s honeydew.”

Nope, that's not custom paint- that's honeydew.
(At least it does bring some shine to the ol' girl!)

Honeydew? Yes, it’s a wonderful, sweet melon and my favorite scientist on the Muppet’s Show, but it’s also the term used for the sticky substance that is excreted from phloem-sucking insects. Scales, adelgids, whiteflies, and aphids all produce honeydew. They pick a spot on a plant leaf or needle and, with their specialized mouth parts, bite down and start sucking the phloem, or plant sap. As with all things eaten, what goes in must come out, and out it comes as honeydew. Then it floats down and finds its way onto things below it.

Like I did with the Falcon, you’ve probably parked a car under a tree seeking shade from the summer sun only to come back and find the windshield sticky with honeydew. Perhaps your deck and railing have become covered with the sticky substance, too, or the sidewalk under a tree. I get calls in the office asking what kind of tree it is that creates the honeydew, or what’s wrong with a tree that's ‘leaking’ sap from above. No one is thrilled to find out it’s actually insect poop that has covered their patio furniture or sunroof.

These shade seekers will find their windshields a sticky mess
at the end of the day as this cottonwood has aphids.

In most areas this time of year, aphids are the creators of honeydew. As one of the only insects that gives live birth, each aphid is born ready to birth to the next generation, and so on. This means that aphids multiply rapidly, and as more are born, more excrete honeydew. One day your deck is fine, and two days later, it’s a sticky mess. And just like that, your honey-do list now includes power washing the deck, scrubbing the outdoor furniture, and washing the car.

Honeydew does have its fans. The hum from the tree near the Falcon isn't the 289 V8 firing all cylinders, but Western Yellowjackets who feed on it and swarm the tree to find it. Ants love it, too, and will roam the plant or tree collecting it and protecting the aphids producing it. 

Plants can be sprayed with an insecticidal soap or pesticides to help control aphids, but I find that just spraying them down with a strong jet of water is effective and causes fewer issues for beneficial insects and the items below the tree. A hard rain will do the same thing and provide relief for a few days, but remember that the aphid population will rebound quickly. Spraying with water again can help keep numbers manageable.

A lower leaf from the cottonwood, sticky with honeydew

For detailed information on how to control aphids on shade trees, add reading CSU Fact Sheet 5.511 to your honey-do list. The control efforts you learn might enable you to knock a few of those other honey-do items of the page.