Adelgid Control: How to Get Rid of Adelgids

This page is a general DIY guide that eliminates adelgids from ornamental trees within your lawn. Using the products and methods suggested you will get control of adelgids. Follow this guide and the recommended products to completely control adelgid infestations.

Hemlock trees are some of the largest trees found in eastern forestry settings and sometimes in ornamental landscaping. Unfortunately, this tree species is most commonly infested with adelids, known as hemlock woolly adelgid, a tiny aphid-like pest that covers itself with a waxy wool. Though small, this invasive insect poses a serious threat to conifers like eastern hemlock trees causing loss of tree needles and limbs then death in properties and forest sites.

This tree-infesting pests spreads at least 15 miles per year by wind, people, birds, or other animals. Adelgids are parthenogenic meaning that all pests are female and produce offspring without mating. Each infestation creates two generations per year. Another factor that makes this pests intimidating is their saliva containing toxic qualities, which causes the needles of hemlock trees to fall and stunt twig growth. Typically, adelgids are cool-weather pests that begin feeding during October and early spring.

Although some hemlock trees recover, the adelgids are a persistent and rapidly growing pest infestation that can eliminate trees within several years. If left untreated, trees become weakened and more susceptible to other insects and disease activity. By following the steps and products listed in our DIY guide you can completely eliminate adelgid populations, which will help to lessen the insecticide application and cost.

Identification

Before you can proceed with a treatment program, you will need to certain that the pest infesting your trees is adelgids. While there are several species of adelgids each with their own defining characteristics, this article will focus on the hemlock woolly adelgid since it is the most encountered pest. Refer to the following characteristics to identify hemlock woolly adelgid.

• Adelgids are tiny insects that cover themselves in a white, waxy, wool-like substance, appearing like small, white bumps. These masses are about the size of a cotton swab, and the insects themselves grow up to be less than 1/16 of an inch in length.
• Nymphs are soft-bodied, wingless, and have short, thick legs. However, they will stay in place and not travel very far. When more mature, they will possess a pair of wings.
• Nymphs possess a coloration of reddish-brown with a small white hair fringe near the front of their bodies. As they mature, the white fringe will form down its back and sides.
• Adult adelgids are dark brown in color with long, five-segmented antennae, small eyes, and textured wings.
• There are two species of adelgid nymphs. The first one, known as sistens, hatches in late spring, wingless, and thrives throughout the late spring to summer. Living for about 9 months in total. The second generation, called progrediens, hatches in early spring and has a mixture of wingless or winged nymphs. These second-generation pests will only live for 3 months from early to late spring. The main focus of the second generation is to spread to other conifer tree species for egg-laying activity.
• Eggs of adelgids are oblong and amber in color. Measuring between 0.36 mm to 0.23 mm wide in large batches from 250 to 300 eggs. These eggs will be covered by the spherical-shaped egg sacs within it's white waxy threads.

Use the image and description above to help you properly identify adelgids. If unsure, then contact us through email or in person at one of our store locations with a picture of the pest infesting your conifer species.

Inspection

After you have confirmation of adelgids, you will need to inspect the area to see where the infestation is most active and the conditions helping it to thrive. Determine the size of the adelgid infestation to help you in your pesticide and treatment application.

Where to Inspect

Adelgids search for suitable homes and nesting sites within conifer trees, usually at the base of the plant leaves or needles. Typically, these pests tend to infest young tree growths like Douglas firs, hemlock, larch, pine, and spruce in forest sites or residential landscapes. The most encountered site of adelgid activity is hemlock tree species since they produce cooler, and darker sheltered environments.

What to Look For

The most common sign of adelgid infestations is the white woolly masses on the underside of branches at the bases of plant leaves, needles, bark, cones, from March to May. When hatched, adelgids can cause yellowing and needle loss or receding branches. If continued feeding occurs, then leaves or needles of tress will become gray and eventually the tree will have bare branches then eventual death.

Treatment

When beginning any pesticide management program, you will need to wear the appropriate personal protective equipment (PPE) such as gloves, long-sleeve shirt, long-sleeve pants, closed toe shoes with socks, mask, safety mask, goggles, apron, overalls or tyvek suit.

Removal of hemlock trees can produce a temporary resolution, but may alter in the loss of other plants or affect certain wildlife activities. The most effective strategy for treating adelgids in your yard is to use long-term insecticides labeled for use adelgids and conifer tree species.

Step 1: Prune Tree Limbs

When present, adelgids often remain in the area they are infesting unless they are second generation pests, progrediens. Either generation of pests is not ideal and should be controlled in the early spring to fall.

Regular pruning of decaying or discolored foliage leaves, stems, and branches can help to eliminate populations. Dispose of discarded foliage by burning or shredding to prevent pests from escaping their eggs sacs.

Step 2: Perform Drench Application with Imidacloprid 2F

To manage adelgids on your property, use an insecticide like Imidacloprid 2F. Imidacloprid 2F is a long-lasting systemic insecticide designed to protect trees, shrubs, and turf. When applied as a drench treatment, the product is absorbed by plants through their roots.

Pests that feed on treated plants will ingest the product and die out. This product is a liquid concentrate, so it will need to be mixed with water before application.

To treat trees, we recommend you apply this product as a drench application with a Solutions Hose End Sprayer.

Apply 0.1 to 0.4 fluid ounces per inch of trunk Diameter at Breast Height in no less than 10 gallons of water per 1,000 square feet.

Apply your solution around the base of the tree. Remove any plastic or barriers that could hinder absorption. In some cases, it can take 60 days or longer for the product to fully translocate into the plant.

Step 3: Apply Foliar Application with Supreme IT

Once your drench application has dried completely, apply an insecticide like Supreme IT. Supreme IT is a bifenthrin-based liquid insecticide concentrate that is labeled to treat over 70 different pests. When applied, Supreme IT will leave a residual chemical barrier that will control pests for up to 90 days after application.

This product is a liquid concentrate, so it will need to be mixed with water before application. For uniform coverage and to reach higher tree canopies, we recommend you mix and apply this product with a Solutions Electric Backpack Sprayer.

Determine how much Supreme IT to use by calculating the square footage of the treatment area. To find this, measure the length and width of the treatment site in feet and multiply (length X width = square footage). 

The application rate for adelgids is 0.25 to 0.5 oz. of Supreme IT per gallon of water per 1,000 sq. ft.

Mix the product in a hose-end sprayer to reach the tree limb canopies and branches. You will first pour the appropriate amount of product into the hose-end sprayer tank and attach to the end of a garden hose. Spray until the correct amount of water is added to the spray tank mixture. 

When spraying trees and shrubs, aim for complete coverage of your target’s foliage and branches. Then, spray shrubbery and ornamentals from above and below to coat all leaf surfaces.

As 2 generation pests, you will need to retreat your trees when 90 days have passed after the first application.

We recommend making applications on a quarterly basis from February, May, August, and November to prevent adelgid activities.

Prevention 

After you have eliminated the presence of adelgids from your trees, you will want to take preventative measures to ensure these pests do not return. Listed below are preventative measures to take to lessen the chances of adelgids returning.

• Deeply water your trees with a strong stream of water to disturb eggs sacs or adelgid activity. Water with an inch of irrigation in the early morning.
• Prune swollen tree limbs and discolored or decaying plant leaves, needles, buds, and stems. This will promote healthy plant growth and remove potential infestation.
• Forest infestations of adelgids can be reported to your local forest health office. Treatments to forestry sites cannot be made by the general public.
• Mow your turf when it reaches a height of 3 inches to remove any potential adelgids that might of landed on your turf, ornamental foliage, or fallen leaves or branches.
• Rake fallen leaves and branches into a bag and then dispose in a sealed outdoor trashcan.
• Finally, make reapplications of Imidacloprid 2F and Supreme IT. Soil drench applications of Imidacloprid 2F can last for up to 1 year, and Supreme IT can last for up to 90 days.

Key Takeaways

What are Adelgids?

• Adelgids are sap-feeding insects that resemble aphids, with the exception that this pest feeds on conifer tree species whereas aphids feed on all plant types.

How to Get Rid of Adelgids

• Adelgids are best controlled by continual applications of systemic insecticides such as Supreme IT, Imidacloprid 2F, and pruning of leaves and stems. Spray the top and bottom of foliage leaves and branches until wet, but not to the point of run-off.

Preventing Adelgids Reinfestations

• We recommend making quarterly applications with Supreme IT and Imidacloprid 2F from February to November to control both generations of adelgids. You will also need to mow, prune, and rake your yard to eliminate suitable habitats.