Aphids are everywhere this year. They may be our No. 1 insect pest this gardening season.

Why are aphids everywhere this growing season?

There is no clear answer. Sometimes insects appear in cycles.

The mild weather with two cold snaps during the winter of 2022-’23 impacted plants, pests and predatory insects.

In the case of aphids, it may be a combination of the spring drought and our gardening routines. We often apply fertilizers in the spring to give our plants a boost of nutrients.

Aphids are attracted to young, tender, fast-growing plant parts rich in nitrogen. Aphids are also attracted to stressed plants. Our plants were drought-stressed this spring. It is a bad combination.

Aphids are small, 1/32 to 1/8 inch, mostly pear-shaped, wingless and totally devoted to eating, or rather, sap-sipping. When their numbers become abundant, the damage they can inflict becomes apparent even if the insect itself is hard to see.

Aphids have piercing-sucking mouthparts that enable them to remove plant fluids from a host. Look for curling, yellowing and stunted leaves, usually at the end of a stem. Make sure that you check underneath the leaves for their hiding places.

Aphids are sap-feeders. All sap-feeders excrete “honeydew,” a sugar-rich sticky liquid, secreted by aphids and some scale insects as they feed on plant sap.

Aphids feed on stems, buds,and flowers, as well as leaves, and their feeding produces honeydew, which is much prized by other insects, such as wasps and ants as a welcome addition to their own food supply.

The sugary honeydew evaporates, making a sticky, shiny mess on the leaves, on your car, or whatever is under the plant. Later, black sooty mold grows on the honeydew, interfering with the plant’s photosynthesis and increasing its messy appearance.

Be on the lookout for natural predators. Ladybugs and especially their orange and black larvae are voracious predators of aphids. Flower fly larvae and lacewing larvae feed on aphids, too.

There are tiny parasitoid wasps that insert an egg into a living aphid, turning it into a round, chubby “mummy” that acts as a nursery for its next generation. Birds, especially warblers and hummingbirds, are consumers of aphids.

How can a gardener manage aphids? You can squish them gently with your fingers. If that is not an option for you, you can blast them with a stream of water from the garden hose.

Be sure to spray up, then spray down to include the undersides of the leaves. Water will knock them off and few will return.

Be sure to look for natural insect predators before treating the aphids.

If you need to control the aphids, a simple treatment with insecticidal soap is also effective.

Remember that a solution made with dish detergent will damage plant tissue, so do not use homemade recipes.

Avoid systemic insecticides, which travel throughout the plant, including the flowers. These products impact good insects like aphid predators and pollinators.

“Growing Green” is contributed by Diane Dorn, Lehigh County Extension Office Staff, and Master Gardeners. Information: Lehigh County Extension Office, 610-391-9840; Northampton County Extension Office, 610-813-6613.