Do Green Grocer Cicadas Cause Damage to Trees and Plants?

Cicadas are fascinating insects known for their distinctive buzzing sounds and periodic mass emergences. Among the various species of cicadas, the Green Grocer cicada (scientifically known as Cyclochila australasiae) is one of the most iconic in Australia. With its vibrant green coloration and loud calls, it often attracts attention from nature enthusiasts and gardeners alike. However, a common question arises: Do Green Grocer cicadas cause damage to trees and plants? In this article, we will explore the biology of Green Grocer cicadas, their life cycle, feeding habits, and potential impact on vegetation to provide a thorough understanding of their relationship with trees and plants.

Understanding Green Grocer Cicadas

Green Grocer cicadas belong to the family Cicadidae and are native to eastern Australia. These cicadas are known for their bright green exoskeletons, often with yellow or black markings, and a loud, continuous buzzing call produced by males to attract females during mating season. They typically appear in large numbers during the warmer months, especially summer, when temperatures rise above 25°C (77°F).

Adult Green Grocers measure approximately 3 to 4 centimeters in length, making them relatively large among cicada species. Their life cycle involves spending several years underground as nymphs before emerging as adults for a brief period ranging from a few weeks to a couple of months.

The Life Cycle of Green Grocer Cicadas

Green Grocer cicadas undergo incomplete metamorphosis with three main stages: egg, nymph, and adult. Understanding their life cycle sheds light on how they interact with trees and plants.

Egg Stage: Adult female Green Grocers lay eggs in small slits or grooves they create in tree branches using their ovipositor (a specialized egg-laying organ). Each female can lay hundreds of eggs over several days.

Nymph Stage: After approximately six weeks, nymphs hatch from the eggs and drop to the ground. They burrow into the soil where they remain underground for several years (typically between 3 to 6 years), feeding on sap from tree roots through specialized piercing-sucking mouthparts.
Emergence & Adult Stage: When development is complete, nymphs tunnel to the surface, shed their exoskeletons (molting), and emerge as winged adults. Adults live above ground for approximately 4-6 weeks to mate and lay eggs before dying off.

This long underground phase is important because it limits the period during which cicadas interact directly with above-ground plant parts.

How Do Green Grocer Cicadas Feed?

Both nymphs and adults feed on plant fluids but target different parts of plants:

Nymphs: Underground feeders that tap into tree roots to extract xylem sap rich in water and nutrients.
Adults: Above ground feeders that insert their mouthparts into twigs and branches to access sap.

Their feeding method involves piercing plant tissues with needle-like mouthparts called stylets. This allows them to suck sap without chewing leaves or causing large visible wounds.

Potential Damage Caused by Green Grocer Cicadas

1. Egg-Laying Damage

The primary source of damage caused by Green Grocer cicadas occurs during egg laying rather than feeding itself. Females cut into young branches or twigs to deposit eggs inside the plant tissue. These cuts can cause:

Flagging: This is when small twigs or branch tips die after egg-laying scars disrupt nutrient flow.
Twig Dieback: Severe or repeated egg-laying can cause multiple twigs to die back.
Aesthetic Damage: For ornamental plants or fruit trees, this damage can be unsightly.

However, although flagging looks concerning, it rarely results in serious harm to mature trees. Most healthy trees recover quickly without long-term impacts.

2. Sap Feeding Effects

While both nymphs and adults suck sap from plants, this usually does not kill or severely weaken trees because:

The volume of sap removed by each cicada is minimal.

Most trees have abundant sap reserves.
Sap feeding does not involve tissue consumption or leaf destruction.

In large emergences with thousands of cicadas present, some stress may occur due to combined feeding pressure but is generally mild.

3. Secondary Effects

Occasionally, egg-laying cuts may serve as entry points for fungal infections or secondary pests if plant defenses are compromised. This risk is low but possible if environmental conditions favor disease development.

Do Green Grocer Cicadas Kill Trees?

The short answer is: No, Green Grocer cicadas do not kill healthy trees.

Although female cicadas scar twigs during egg laying causing localized damage, mature trees typically tolerate this damage with minimal impact on overall health or growth. Similarly, the sap feeding behavior of nymphs underground and adults above ground does not significantly harm root systems or foliage.

In fact, many trees have coexisted with cicada populations for thousands of years without suffering population-level declines due to these insects’ activities.

Impact on Young Trees and Sensitive Plants

While mature trees generally withstand cicada activity well, young saplings or stressed plants might be more susceptible to damage:

Young branches are more fragile and extensive flagging could stunt growth temporarily.
Repeated infections at egg-laying sites could increase vulnerability.

Gardeners growing young or newly planted fruit trees should monitor for excessive twig dieback during cicada seasons but severe damage remains uncommon.

Ecological Benefits of Green Grocer Cicadas

Despite concerns about potential damage, it is important to recognize several benefits Green Grocer cicadas provide within ecosystems:

Soil Aeration: Nymph burrowing helps aerate soil promoting root health.
Nutrient Cycling: When adult cicadas die off en masse after mating season their bodies decompose enriching soil nutrients.

Food Source: Cicadas serve as an essential food source for birds, reptiles, mammals, and other predators helping maintain biodiversity.
Pollination Indirectly: While not pollinators themselves, their activity helps maintain healthy tree populations that support pollinators.

Managing Cicada Damage in Gardens

For those concerned about potential twig dieback or aesthetic damage caused by Green Grocer cicadas in home gardens or orchards, some practical measures include:

Physical Barriers: Covering young trees with fine mesh netting can prevent female cicadas from accessing branches for egg-laying.
Pruning: Removing flagged twigs after egg deposition helps maintain plant appearance and health.
Watering & Fertilizing: Keeping plants well-watered and nourished improves resilience against stressors including insect damage.

Avoid Pesticides: Using pesticides against cicadas is generally discouraged because:
Cicada adults are short-lived.
The impact on other beneficial insects can be negative.
Damage levels do not usually justify chemical intervention.

Conclusion

Green Grocer cicadas are remarkable insects celebrated for their vibrant colors and noisy presence during summer months in eastern Australia. While females do cause some localized damage through egg laying that results in flagged twigs or minor dieback on trees and shrubs, this damage is typically superficial and temporary on mature plants.

Their feeding behavior—both underground as nymphs sucking root sap and above ground as adults tapping branch sap—does not lead to significant harm or death of healthy trees. Young plants may experience some stress from extensive twig flagging but serious injury remains rare.

Ecologically speaking, Green Grocer cicadas play valuable roles in nutrient cycling and food webs supporting diverse wildlife communities.

For gardeners concerned about cosmetic damage during cicada seasons, simple management techniques such as netting young trees or pruning twig dieback can help minimize effects without resorting to harmful chemicals.

Ultimately, Green Grocer cicadas should be viewed as a natural part of Australia’s forest ecosystems—a seasonal visitor whose presence enriches biodiversity more than threatens vegetation health.