Do Dog-Day Cicadas Cause Damage to Trees and Shrubs?

Dog-day cicadas, known for their loud, buzzing calls during the hottest days of summer, are a familiar sound in many parts of North America. These insects have been around for millions of years and play a unique role in the ecosystem. However, gardeners, landscapers, and homeowners often wonder whether dog-day cicadas cause damage to trees and shrubs. This article explores the biology of dog-day cicadas, their life cycle, behavior, and the extent to which they affect trees and shrubs.

What Are Dog-Day Cicadas?

Dog-day cicadas belong to the family Cicadidae and are commonly referred to as annual cicadas or dog-day cicadas due to their emergence during the “dog days” of summer—typically July and August. Unlike periodical cicadas, which emerge every 13 or 17 years, dog-day cicadas appear every year.

Adult dog-day cicadas are characterized by their stout bodies, clear membranous wings, and distinctive loud buzzing sounds produced by specialized structures called tymbals. These noises are primarily mating calls made by males to attract females.

The Life Cycle of Dog-Day Cicadas

Understanding the life cycle of dog-day cicadas is crucial to assessing their impact on plant health:

Egg Stage: After mating, female cicadas lay eggs in slits they cut into small twigs and branches of trees and shrubs.

Nymph Stage: Eggs hatch after six to ten weeks, and the tiny nymphs drop to the ground where they burrow underground. They feed on sap from tree roots for two to five years depending on species.
Emergence: When fully developed, nymphs emerge from the soil and climb up vegetation or other vertical surfaces.
Adult Stage: They molt into adult cicadas, live for about four to six weeks above ground, mate, lay eggs, and die.

How Dog-Day Cicadas Interact With Trees and Shrubs

Egg-Laying Behavior

The primary interaction between dog-day cicadas and plants occurs when females use their ovipositors (egg-laying appendages) to cut slits into small branches or twigs. This process is called “oviposition.”

Female cicadas prefer young branches that are less than one centimeter in diameter.
They make multiple small cuts in a single branch to deposit eggs.

The number of eggs laid can range from 10 to 20 per branch.

Feeding Habits

Both nymphs and adults feed on plant fluids:

Nymphs: Feed underground on root xylem sap.

Adults: Pierce stems or branches with mouthparts to consume sap.

Generally, the feeding of adults is minimal compared to nymphs because adults live only a few weeks.

Do Dog-Day Cicadas Cause Significant Damage?

Impact of Egg-Laying on Branches

When females insert their eggs into twigs, this causes some physical damage:

Flagging: One visible effect is “flagging,” where small branches or twig tips wilt and die because egg-laying disrupts nutrient flow or causes wounds that lead to tissue death.
Branch Dieback: Multiple oviposition sites can cause sections of a branch to die back.
Aesthetic Damage: For ornamental plants or young trees, this twig dieback can be unsightly.

However, in most cases:

The damage is limited to small twigs or branches rather than large limbs.
Mature trees with robust growth usually tolerate this damage without long-term harm.

The overall structural integrity of trees remains intact.

Nymph Feeding Damage

Nymphs feed on root sap but typically do not cause harmful effects because:

Their feeding occurs over several years at low densities.

Root systems of healthy trees can compensate for minor sap loss.
High densities might stress young or already weakened plants but rarely kill them outright.

Adult Feeding Impact

Adult feeding is negligible in terms of plant damage because:

Adults feed lightly during their brief lifespan.
They tend to move between many plants rather than continuously feeding on one.

Comparison With Other Insects

Unlike wood-boring beetles or aphids that can cause significant damage through larval feeding or disease transmission, dog-day cicadas do not bore deeply into woody tissue nor spread pathogens associated with systemic decline.

Which Trees Are Most Affected?

Dog-day cicadas show preference for certain tree species when laying eggs:

Deciduous hardwood trees such as oaks, maples, hickories, and walnuts are common hosts.
Fruit trees such as apple, cherry, peach, and pear may be occasionally used.

Shrubs with sufficiently woody twigs may also be affected but usually less so than trees.

Young trees or saplings are more vulnerable to twig dieback caused by oviposition cuts because smaller branches represent a larger proportion of their overall structure.

Can Cicada Damage Be Prevented or Controlled?

Controlling dog-day cicadas is challenging due to their widespread presence and life cycle. However, several strategies can minimize damage:

Physical Barriers

Using fine netting or mesh covers over young trees during peak egg-laying periods (late July through August) can prevent females from accessing branches.

Pruning

Removing dead or flagging twigs promptly after egg-laying season reduces aesthetic damage and prevents secondary infections.

Maintaining Tree Health

Strong cultural care practices improve resilience against insect stress:

Proper watering
Mulching
Soil fertility management

Avoiding unnecessary pruning during vulnerable times

Chemical Controls

Insecticides are generally not recommended because:

Cicada emergence is brief and localized.

Broad-spectrum insecticides may harm beneficial insects and pollinators.

If chemical treatment is considered necessary (for example in commercial orchards), timing application just before emergence may reduce egg-laying but must be done carefully following regulations.

Ecological Benefits of Dog-Day Cicadas

While concerns about damage are valid for certain situations, it’s important to recognize the ecological role of dog-day cicadas:

Food Source: They provide abundant food for birds, mammals, reptiles, and other insects during emergence.
Soil Aeration: Nymph burrowing helps aerate soil.
Nutrient Cycling: Decomposition of dead adults adds nutrients back into ecosystems.

This balance means that in healthy natural systems, dog-day cicadas contribute positively despite minor plant damage.

Conclusion: Should You Worry About Dog-Day Cicada Damage?

For most homeowners and gardeners, dog-day cicada damage to trees and shrubs is minimal and mostly cosmetic. Mature trees tolerate occasional twig dieback without long-term harm. Problems arise mainly when young trees or valuable ornamental plants experience heavy egg-laying pressure leading to excessive flagging.

Preventative measures like netting or pruning can help protect vulnerable plants if desired. Maintaining overall tree health is the best defense against potential stress caused by cicada activity.

Ultimately, while dog-day cicadas may cause some localized twig damage during their summer emergence, they do not pose a major threat to tree or shrub health. Their presence is a natural part of summer’s soundscape that supports broader ecological balance.

By understanding the biology and behavior of dog-day cicadas along with proper landscape management techniques, you can enjoy these fascinating insects’ seasonal chorus without undue concern over plant damage.