From the golden-rose blush of aspen groves to the sharp, sappy smell of a blue spruce, the trees of Colorado are a beloved staple throughout our state’s outdoor spaces. But while trees enhance property value and curb appeal, they can also attract a variety of unwanted pests, like wasps, that pose a risk to health and wellbeing.
In today’s blog, we hope to help homeowners and business owners understand why trees attract pests, as well as gain the know-how to protect their property, including knowing when to hire professional pest control services. Let’s dive in!
Aphids and Honeydew and Wasps! Oh, My!
If you’ve ever noticed wasps or yellowjackets circling a particular tree in your yard, the tree itself usually isn’t to blame. The real draw is often a chain reaction started by sap-feeding insects. Aphids and scale insects tap into a tree’s sap and release a sticky, sugary residue called honeydew. This honeydew doesn’t just coat leaves and branches—it can drip onto patios, cars, and anything else beneath the canopy.
That sugary coating creates two problems. First, it encourages sooty mold, a dark fungus that spreads across leaves and puts extra stress on a tree already dealing with insect pressure. Second—and most frustrating for homeowners—it becomes a beacon for wasps. Wasps actively hunt for both honeydew and the insects that produce it, so a tree loaded with aphids suddenly looks like an easy food source.
These wasp swarms aren’t a sign that the tree is inherently “attractive” to stinging insects. Instead, secondary pests have turned the tree into an all-you-can-eat buffet. Reducing aphid activity and keeping the tree healthy go a long way toward lowering wasp interest.
Healthy Trees Naturally Repel Pests
Healthy trees—whether pines, aspens, maples, elms, or ornamentals—carry their own built-in defenses. Pine trees, for example, release aromatic terpenes that naturally discourage many problem insects. When a tree becomes stressed by drought, crowding, or poor pruning, those defenses weaken. Stressed pines produce fewer terpenes, and other species lose similar protective strengths. Once a tree’s defenses drop, sap-feeding insects like aphids, scales, and mites move in, and their presence quickly draws wasps looking for easy food.
Residential Trees Most Commonly Associated With Honeydew Problems
Lindens
Lindens tend to show aphid activity through a glossy, varnish-like shine on their broad leaves—often one of the first indicators homeowners notice. The leaves may remain green but look wet, even on hot, dry days. As the season progresses, sidewalks or vehicles beneath a linden often develop a slippery coating. Heavy infestations can also cause the soft, heart-shaped leaves to droop slightly, giving the tree a tired appearance.
Crabapples
Crabapples reveal stress differently. Their small leaves may become puckered or distorted, especially around the midrib, where aphids like to feed. New shoots sometimes appear stunted, and the tree may produce fewer blossoms the following year. Because crabapples are prone to producing dense clusters of buds and fruit, aphid damage often shows up as uneven fruit development—tiny apples that stay undersized or fall prematurely.
Willows
Willows respond to sap-feeding insects with changes in their long, narrow leaves. Instead of curling inward like many species, willow leaves often twist along their length or develop a silvered appearance, almost as if dusted with powder. The flexible branches may shed leaves earlier than normal, and entire branch tips can take on a wilted, rope-like look. These symptoms usually follow periods of inconsistent watering or heat stress, which make willows especially appealing to aphids.
Japanese Maples
Japanese maples show stress in their delicate, often deeply cut leaves. Aphid pressure can cause the foliage to develop fine stippling or pale patches where color looks washed out. On laceleaf varieties, sections of the canopy may sag or flatten rather than holding their usual airy shape. Smaller branches may also show bark that appears slightly swollen near the tips—an indicator of feeding around tender new growth.
Birches
Birches typically display aphid problems in the upper canopy first. Their triangular leaves may develop speckled yellow patches that contrast sharply with otherwise bright green foliage. Catkins may dry out early or fall before maturing. Some birches also shed tiny flecks of frass (insect debris) that collect on patios or deck railings below, a subtle but tree-specific sign of sap-feeding insects working high in the crown.
How to Prevent Trees From Attracting Excessive Problem Insects
- Prioritize basic tree care: water deeply, mulch properly, prune with intention, give trees enough space, and protect trunks from mower and string-trimmer damage.
- Watch for early warning signs: sticky leaves, distorted foliage, or visible clusters of sap-feeding insects on new growth.
- Support natural predators: use sustainable pest control techniques, plant flowers that attract lady bugs and other beneficial insects, and avoid heavy use of broad-spectrum sprays that wipe out helpful species.
- Limit environmental stress: don’t over-fertilize, loosen compacted soil when possible, and respond quickly to drought conditions.
- Call an arborist when needed: seek professional help if you see branch dieback, thinning crowns, boring holes in the trunk, or pest activity that extends well beyond normal seasonal levels.
When to Call Bug Control Specialist
Reach out when wasps or yellowjackets start acting aggressively around your trees, when outdoor areas become difficult to use, or when nests appear near play spaces, patios, or rooflines. Safety concerns for kids, pets, or anyone with allergies are reason enough to call wasp exterminators.
Bug Control Specialist handles safe wasp removal, seasonal management plans, and practical guidance for reducing the conditions that attract stinging insects. In addition, we know local arborists and can recommend you to a tree professional to make sure your trees stay healthy. If wasps are taking over your yard, contact Bug Control Specialist and reclaim your space!