Cottonwood Borer Bite: Is It Poisonous? Fact Check and Safety Tips

The cottonwood borer (Plectrodera scalator) is a type of longhorned beetle known for infesting trees like cottonwood, poplar, and willow. Adult cottonwood borers have a distinct black and white pattern and can grow up to 1.5 inches in length. Their larvae are large, white, and deeply segmented grubs that can reach nearly 2 inches when fully grown. These insects are known for causing damage to trees but are rarely a threat to humans.

The question often arises – is the cottonwood borer bite poisonous? In general, their bites are not known for being venomous or harmful to humans, as they mostly feed on tree bark and wood. Although they might look intimidating, these beetles are not typically considered dangerous to people.

However, if you come across a cottonwood borer, it’s best to avoid handling it unnecessarily. This is simply to prevent any possible minor injury from a defensive bite. Overall, there’s no need for panic, as these wood-boring insects pose no significant threat to human health.

Cottonwood Borer Overview

Identification

The Cottonwood Borer (Plectrodera scalator) is a large longhorn beetle that can grow up to 1.25 inches in length. It has a distinct black and white coloration and its antennae are as long, or sometimes even longer, than its body.

Habitat

These beetles are primarily found in the U.S., mainly in North America, where they breed in the bases and roots of living cottonwood, poplars, and willows¹.

Life Cycle

The life cycle of the Cottonwood Borer consists of several stages:

• Eggs: Female beetles lay their eggs in August at the base of host plants².
• Larvae: Cottonwood Borer larvae are legless roundheaded borers that can grow up to 1.5 inches long². They bore into tree roots and cause damage.
• Pupa: In this stage, the larval form transforms into that of a mature adult.
• Adults: Adult beetles emerge and cause damage while feeding on young trees, but most of the damage comes from the larval stage¹.

Damage to host trees:

• Larvae cause most of the damage by hollowing, partially severing, or girdling trees¹.
• Adults feed on young trees, leading to additional damage¹.

Comparison table of Cottonwood Borer and Asian Longhorn Beetle:

Host Trees and Damage

Infested Trees and Host Plants

Cottonwood borers are wood-boring beetles that primarily infest cottonwood, poplar, and willow trees. They can also be found in other tree species like birch.

Examples of host trees include:

• Cottonwood trees
• Poplars
• Willows
• Birch

Symptoms of Infestation

Infestations can cause various symptoms, including:

• Holes in the bark
• Reddish frass (insect waste) in bark crevices or near the tree base
• Girdled branches and twigs
• Dieback in the tree canopy

Damage to Trees and Property

Cottonwood borers can cause significant damage to host trees, especially young ones. They tunnel through the inner bark and may reach the tree’s root system. In severe infestations, larvae create girdling tunnels which can damage the tree’s vascular system, causing wilting or even death.

Below is a comparison of healthy and infested trees:

Some consequences of cottonwood borer infestations include:

• Damaged or dead trees
• Girdled tree trunks
• Wilted or discolored leaves
• Potential property damage from weakened trees falling

The cottonwood borer does not have venom or poison glands, and its bite is not considered dangerous or poisonous to humans. However, infested trees may suffer damage or even die, so it is essential to address infestations promptly.

Reproduction and Development

Mating and Egg-Laying

Cottonwood borers are large, robust long-horned beetles with black antennae as long or longer than the body (source). The mating process begins with male beetles searching for female beetles using their long antennae to locate them. After fertilization, female beetles lay eggs on or around the roots of host plants.

Some key features of cottonwood borer mating and egg-laying:

• Male and female beetles participate in fertilization
• Eggs are laid on or around plant roots

Development and Metamorphosis

Cottonwood borer larvae cause most of the damage by feeding on and hollowing out the roots and lower trunk of host trees, like cottonwood, poplars, and willows (source). As the larvae grow, they undergo metamorphosis, passing through several stages before reaching adulthood. They pupate within the tree, and adult cottonwood borers emerge through holes in the trunk or branches.

A comparison table between Asian longhorned beetle and cottonwood borer:

Characteristics of cottonwood borer development:

• Larvae feed on and hollow out tree roots
• Undergo several stages of metamorphosis
• Pupation occurs within the tree
• Adults emerge through holes in the trunk or branches

Prevention and Control

Monitoring and Identification

To prevent and control cottonwood borer infestations, it’s important to monitor and identify them. The cottonwood borer is a type of longhorn beetle that has black and white-striped patterns, black antennae, and a cylindrical body. They belong to the roundheaded borers group attacking host plants like cottonwoods and other trees. Some key identification features include:

• Striped pattern
• Black antennae
• Cylindrical body

You can monitor their presence by looking for signs such as sawdust and holes in the bark of the tree, as well as damaged leaf stems. Also, stay alert for their predators, such as birds and spiders, as an increase in their presence may indicate a cottonwood borer infestation.

Chemical Control

In some cases, chemical control might be necessary to manage cottonwood borer populations. Insecticides can be effective when applied at the appropriate time, usually when adult insects lay eggs on the tree trunks. However, chemical control has its pros and cons:

Pros:

• Can effectively reduce borer populations
• Protects trees from further damage

Cons:

• Can be harmful to non-target species
• May lead to pesticide resistance in borers

Cultural and Physical Control

Cultural and physical control methods include maintaining tree health, proper pruning, and removing infested firewood. These approaches provide a more eco-friendly alternative to chemical control. Here are some tips:

• Maintain tree health: Keep trees well-watered and fertilized
• Prune properly: Remove dead and damaged branches
• Remove infested firewood: Dispose of infested wood to avoid spreading borers

In areas prone to high winds, such as the United States’ Rocky Mountains, planting windbreaks can also protect host plants from wind damage, reducing the risk of cottonwood borer infestations.

Conclusion

The cottonwood borer, scientifically known as Plectrodera scalator, is a large, long-horned beetle. Its larvae can cause significant damage to cottonwood, poplar, and willow trees.

Cottonwood borer bites are not known to be poisonous. If you are bitten, it’s essential to maintain a watchful eye for potential allergic reactions or infections. However, the chances of being bitten are relatively low.

Pros:

• Cottonwood borers aren’t hazardous to humans.
• Bites are generally uncommon.

Cons:

• These beetles can cause significant tree damage.
• If bitten, individuals might experience an allergic reaction or infection.

As a result, cottonwood borers pose primarily a risk to trees rather than to humans. It is critical to focus on preventing tree damage when dealing with these insects.