Asian Longhorned Beetle 

Insecticide Treatments

The U.S. Department of Agriculture’s (USDA) Animal 

and Plant Health Inspection Service (APHIS) and its 

partners use insecticide treatments as part of an

integrated approach to eradicate Asian longhorned beetle 

(ALB). This combined approach includes imposing

quarantines, conducting tree inspections, removing 

infested trees, and sometimes removing at-risk host trees.

Why is insecticide used to fight ALB?

We use insecticide to reduce the spread of ALB from

currently infested areas. It kills beetles that feed on

the leaves and twigs of treated trees. It is also effective

against the early larval stages of the beetle that feed 

on the inner, growing layer of the tree. As a result, 

the insecticide treatments decrease the number 

of beetles in an area and prevent new trees from 

becoming infested.

What insecticide does the ALB program use?

The generic name of the insecticide is imidacloprid. 

It is a systemic insecticide commonly used to control 

both agricultural and residential insect pests, such 

as aphids, cockroaches, termites, soil insects, thrips, 

whiteflies, and some beetles. It is also used in flea 

and tick prevention products for pets, and it has been

sold in the United States since 1994. Imidacloprid

is registered with the U.S. Environmental Protection 

Agency (EPA) under the Federal Insecticide, Fungicide, 

and Rodenticide Act and is approved for ALB eradication

program use.

When does the ALB program use insecticide 

treatments on trees?

When deciding whether to treat trees with imidacloprid,

APHIS and State officials consider several important

factors, including environmental and biological issues, 

the scale of an infestation, recent ALB survey results, 

and cost. Insecticide treatments are used only on trees 

that are not known to be infested. The treatment kills 

beetles or larvae that try to feed on the tree and helps 

prevent it from becoming infested.

How are insecticide treatments used?

The insecticide is used according to product label

requirements and is applied through either tree trunk 

or soil injections. Trunk injections are applied directly 

into the tree trunk using a specialized device. Soil

injections are applied directly into the soil at the base 

of trees. The number of injections (either trunk or soil) 

per tree depends on the size of the tree. With each

method, the tree’s vascular system pulls the insecticide

upward into the stems, twigs, and foliage where beetles 

will encounter it as they feed and lay eggs.

What species of trees are treated with insecticide?

Tree species that could receive treatments include 

maple and box elder, horse chestnut and buckeye, 

mimosa, birch, katsura tree, ash, golden raintree, 

sycamore and London planetree, poplar, willow,

mountain ash, and elm. Once an area is identified for 

treatments, it is most effective to treat all host trees 

within that area.

When do applications take place?

Imidacloprid treatments can be effective against ALB 

when applied in the spring, early summer, or fall—either

before adult beetle emergence or when adults are feeding 

and laying eggs. It takes 1 to 3 weeks by trunk injection 

and up to 3 months by soil injection forimidacloprid to 

Imidacloprid treatment injection device
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distribute throughout the tree, depending on the tree’s 

size and health and on weather conditions.

Can insecticide be used to treat infested trees 

instead of removing them?

Unfortunately, no. Variability in treatments, weather

conditions, and overall tree health can result in uneven 

insecticide distribution within a tree and prevent the 

insecticide from killing all ALB in an infested tree. 

Also, the insecticide is not effective against the later 

larval stages that spend most of their time inside the 

heartwood of the tree where treatment will not reach 

them. These larvae can continue to grow inside the

treated tree, develop, and still emerge as adult beetles. 

All infested trees must be removed because that is the 

most effective way to completely eliminate the beetle. 

Even treated trees are removed and destroyed if they 

are later found to be infested. 

What research has been done on the use of 

imidacloprid to control ALB?

USDA and Chinese researchers conducted lab and field 

tests in China and the United States. Out of multiple 

insecticides tested, imidacloprid proved to be most 

effective. Specifically, the testing indicated that 

imidacloprid was effective against adult beetles as 

they feed on small twigs and against young larvae 

as they feed beneath the bark. Imidacloprid has been 

very well studied for other uses as well, with many 

articles published in international, peer-reviewed 

scientific journals.

How will these treatments affect the 

environment?

Imidacloprid treatments are applied per product 

label requirements designed to protect human health 

and the environment. The precise placement of injection

treatments and the measures used to ensure precision 

during applications help prevent potentially adverse 

environmental effects. Also, imidacloprid residues 

are limited to the treated tree and its root area. 

The degradation process, or natural breakdown of 

these residues, further minimizes any impact on 

the environment. 

Can imidacloprid harm bees? And are there 

alternatives?

EPA issued a preliminary risk assessment for 

imidacloprid suggesting that some aerial applications 

may harm bees. The risk assessment did not show any 

adverse effects to bees from tree trunk or soil injections. 

USDA conducted a study in Massachusetts and New York 

that demonstrated applications made to control ALB do 

not expose bees to harmful levels of imidacloprid. We 

continue to evaluate alternatives, but at this time none 

are as effective against ALB as imidacloprid.

For More Information

To learn more about imidacloprid, go to 

pubchem.ncbi.nlm.nih.gov/compound/imidacloprid. 

For more information on ALB, visit 

www.aphis.usda.gov/pests-diseases/alb.

Adult Asian longhorned beetle (ALB) shown on wood, chewing an 

oviposition site (egg site)