Are Double Drummer Cicadas Harmful to Your Garden Plants?

Cicadas have long fascinated gardeners and nature enthusiasts alike. Their distinctive buzzing and periodic mass emergences are a spectacle of the insect world. Among the various types of cicadas, the Double Drummer Cicada stands out because of its striking appearance and loud calls. However, for gardeners, the question often arises: Are Double Drummer Cicadas harmful to garden plants?

In this article, we will explore the biology and behavior of Double Drummer Cicadas, their potential impact on garden plants, and best practices for managing these insects in your garden.

What Are Double Drummer Cicadas?

Double Drummer Cicadas are among the largest cicada species in Australia. Named for the two prominent black drums (tymbals) on their abdomen that produce their characteristic sound, these cicadas are both visually impressive and acoustically powerful.

Characteristics

• Size: Adults can reach up to 4–5 centimeters in length.
• Color: They typically have green wings with black veins and a body that features contrasting green and black markings.
• Sound: Their calls are loud and rhythmic, often heard during warm days in spring and summer.

Life Cycle

Like other cicadas, Double Drummers spend most of their lives underground as nymphs feeding on sap from tree roots. After several years—sometimes up to 5 or more—they emerge as adults to mate and lay eggs.

How Do Double Drummer Cicadas Interact with Plants?

Understanding the impact of Double Drummer Cicadas on plants requires a look at both their feeding habits and reproductive behavior.

Feeding Habits

• Nymphs: Underground nymphs feed on xylem sap from roots of trees and shrubs. This feeding is generally not harmful unless there is an extremely high population density.
• Adults: Adult cicadas feed by piercing the stems of branches with their mouthparts to sip sap. While this can cause some stress to plants, adult feeding is usually short-lived (a few weeks) since adults live only long enough to reproduce.

Egg Laying Behavior

Adult female cicadas lay eggs by cutting slits into small twigs or branches using a specialized ovipositor. They deposit eggs inside these cuts where they will hatch into nymphs, which then drop to the ground and burrow underground.

• This egg-laying can cause physical damage known as flagging — where small branches die back due to injury.
• The damage is generally limited to young or thin branches rather than main stems or trunks.
• In large infestations, extensive flagging can reduce plant vigor or affect fruit production.

Are Double Drummer Cicadas Harmful to Garden Plants?

Potential Damage

In general, Double Drummer Cicadas do not pose a severe threat to well-established garden plants or mature trees. The reasons include:

1. Short Adult Lifespan: Adults live only a few weeks; thus, feeding damage is temporary.
2. Selective Egg-Laying: Females prefer smaller twigs for egg laying rather than main structural branches.
3. Resilience of Trees: Healthy trees can usually heal or compartmentalize egg-laying wounds without lasting harm.
4. Nymph Feeding is Minimal: Root feeding by nymphs typically does not injure mature plants significantly.

Situations Where Damage May Occur

• Young Trees or Seedlings: These may suffer more because even small branch loss can affect growth.
• High Population Density: In outbreak years when thousands of cicadas emerge, cumulative damage may stress plants.
• Certain Plant Species: Some species may be more vulnerable to branch flagging or sap loss.

Effects on Fruit Trees and Ornamental Plants

Fruit trees might show some reduction in yield if excessive twig damage occurs during egg-laying periods. However, this impact tends to be minor and short-term. Ornamental shrubs could experience unsightly branch dieback but usually recover fully by the next growing season.

Benefits of Double Drummer Cicadas in Gardens

While some concerns exist about harm, it’s important to recognize positive ecological roles played by these insects:

• Soil Aeration: Nymph burrowing helps aerate soil around roots.
• Nutrient Cycling: After they die, their bodies decompose and enrich soil nutrients.
• Food Source: Cicadas provide food for birds, mammals, reptiles, contributing to biodiversity.
• Pollination Assistance: Though not primary pollinators, their presence supports a healthy ecosystem balance which indirectly benefits plant pollination.

How to Manage Double Drummer Cicadas in Your Garden

If you wish to minimize any potential harm while preserving ecological benefits, here are practical tips:

Protective Measures

1. Physical Barriers: Use fine netting over young or vulnerable plants during peak egg-laying times.
2. Pruning: Remove flagged twigs after cicada emergence to reduce stress on plants.
3. Watering and Fertilizing: Keep plants healthy with adequate water and nutrients to improve resilience.

Avoid Chemical Pesticides

Chemical controls are generally unnecessary for cicadas because:

• Their damage is rarely severe enough to justify pesticide use.
• Pesticides may harm beneficial insects and disrupt garden ecosystems.
• Cicada adults are difficult targets due to their mobility.

Encourage Natural Predators

Birds such as kookaburras and magpies feed on cicadas and help keep populations balanced naturally.

Final Thoughts: Should You Worry About Double Drummer Cicadas?

For most home gardeners, Double Drummer Cicadas are more of a fascinating seasonal event than a destructive pest. Their presence signals a healthy environment with strong native insect populations.

While some minor damage may occur especially during mass emergences, mature garden plants typically withstand this without permanent harm. Young trees may benefit from extra care during cicada season but rarely need drastic interventions.

By understanding cicada biology and using simple management strategies, you can coexist peacefully with these remarkable insects while protecting your garden’s health and beauty.

References:

• Australian Museum: Cicadas
• Department of Agriculture & Water Resources: Managing Cicada Damage
• University Extension Publications on Insect Pests in Horticulture