Pest Control
How to Exterminate Cicadas: Targeted Yard Defense & Tree Protection
The Reality of Cicada Eradication: Why Broadcast Spraying Fails
When homeowners search for how to exterminate cicadas, they are often met with outdated advice recommending broad-spectrum chemical bombing. This approach is an ecological and financial failure. Periodical cicadas (Magicicada species) emerge in broods numbering in the billions per square mile, while annual dog-day cicadas (Neotibicen species) appear in dense localized clusters every summer. Attempting to chemically exterminate an entire yard is futile; the sheer volume of emerging nymphs and flying adults will quickly overwhelm any residual pesticide barrier.
Furthermore, cicadas do not damage turfgrass. Nymphs feed on deep root xylem for years without killing the lawn, and adults do not eat grass. The actual threat is oviposition damage (flagging) to woody plants. Female cicadas use their ovipositors to slit the bark of young branches (typically 1/4 to 1/2 inch in diameter) to lay eggs, causing the branch tips to wither and break. Therefore, professional yard defense focuses on exterminating cicadas from specific vulnerable zones rather than the entire property.
The 3-Tier Cicada Defense Matrix
Selecting the right intervention depends on your budget, the age of your trees, and local ecological regulations. Use this decision matrix to determine your primary defense strategy.
| Defense Tier | Methodology | Target Stage | Efficacy Rating | Est. Cost (1/4 Acre) | Best Use Case |
|---|---|---|---|---|---|
| Tier 1: Physical | 1/4-inch mesh netting | Adult females | 98% (Highest) | $80 - $150 | Young trees, saplings, high-value ornamentals |
| Tier 2: Biological | Entomopathogenic fungi | Emerging nymphs / Adults | 75% - 85% | $120 - $200 | Eco-sensitive zones, large shrubs, perimeter defense |
| Tier 3: Chemical | Pyrethroid contact sprays | Adults on contact | 60% - 80% | $50 - $90 | Severe infestations on mature trees, immediate knockdown |
Tier 1: Physical Extermination via Exclusion (The Gold Standard)
According to entomologists at the University of Maryland Extension, physical barriers remain the only 100% effective method to stop cicada damage without introducing toxins into the local food web. You are not killing the insect; you are exterminating its access to your vulnerable plants.
Step-by-Step Netting Protocol
- Monitor Soil Temperatures: Periodical cicada nymphs emerge when the soil at a 6-inch depth reaches exactly 64°F (17.7°C). Begin netting when soil temps hit 62°F.
- Select the Right Mesh: Purchase UV-stabilized polypropylene netting with a maximum aperture of 1/4 inch (0.6 cm). Standard bird netting (1/2 inch or larger) is useless; cicadas will easily crawl through it.
- Wrap the Canopy: Drape the netting over the entire canopy of trees with trunks under 4 inches in diameter. Do not just wrap the trunk; females will land on the highest reachable branches.
- Seal the Base: Gather the excess netting at the base of the trunk and secure it tightly with zip ties or heavy-duty twine. If there is a gap at the soil line, crawling nymphs will climb the trunk and emerge inside the net.
- Removal Timing: Leave netting in place for 4 to 6 weeks after the first emergence until adult die-off is complete and the chorus stops.
Tier 2: Biological Warfare Using Entomopathogenic Fungi
If you must actively kill the population to reduce noise and carcass buildup, biological pesticides offer a targeted approach that spares beneficial pollinators like bees and butterflies. The most effective biological agent against cicadas is the fungus Beauveria bassiana.
How Beauveria bassiana Works
When cicadas crawl through treated soil or land on treated foliage, microscopic fungal spores attach to their exoskeleton. The spores germinate, secrete enzymes to dissolve the chitin cuticle, and penetrate the insect's body. The fungus then consumes the cicada from the inside out, eventually killing it and erupting through the shell to release more spores. This creates a localized, self-sustaining extermination effect.
Expert Application Tip: BotaniGard ES
Use a commercial formulation like BotaniGard ES (containing Beauveria bassiana strain GHA). Mix at a rate of 1 to 2 fluid ounces per gallon of water. Apply using a pump sprayer directly to the lower 3 feet of tree trunks and the surrounding soil emergence zones. Crucial: UV light degrades fungal spores rapidly. Apply only at dusk or on heavily overcast days, and reapply every 7 days during peak emergence.
Tier 3: Chemical Interventions and Knockdown Sprays
Chemical extermination is a last resort. Broad-spectrum insecticides will kill cicadas on contact, but they also devastate local bee populations and aquatic ecosystems if runoff occurs. If you must use chemicals, restrict applications to the trunks and lower branches of specific trees, avoiding broadcast lawn spraying.
Recommended Active Ingredients
- Bifenthrin (e.g., Talstar P Professional Insecticide): A synthetic pyrethroid that provides a rapid knockdown. Mix rate is typically 1 fl oz per gallon of water, yielding enough to treat 1,000 sq ft. Cost: ~$45 per quart. It has a residual effect of up to 30 days on bark.
- Lambda-cyhalothrin (e.g., Demand CS): A micro-encapsulated pyrethroid that survives UV degradation better than standard emulsifiable concentrates. Cost: ~$60 per 8 oz bottle. Excellent for coating the lower trunks of mature trees where netting is impossible.
Warning: Pet Toxicity and Chitin Blockages
Cicadas themselves are not toxic to dogs or cats. However, the exoskeletons are made of indigestible chitin. If your dog gorges on dozens of cicadas, it can cause severe gastrointestinal blockages requiring emergency veterinary surgery. Furthermore, if you apply Bifenthrin to your yard and your pet eats a poisoned cicada, secondary pesticide toxicity can occur. Keep pets indoors during peak swarm hours (mid-morning) and restrict access to chemically treated zones until the spray is completely dry.
Post-Swarm Yard Recovery and Cleanup
Once the 4-to-6-week mating cycle concludes, the yard will be littered with thousands of carcasses and shed exoskeletons. Do not use a chemical defoliant or excessive water to wash them away. Instead, use a heavy-duty leaf rake to gather the bulk of the carcasses and add them to your compost pile. Cicada bodies are incredibly rich in nitrogen and phosphorus, acting as a high-grade organic fertilizer as they break down.
For the remaining shells embedded in the turf, simply run your lawn mower with a mulching blade set to a height of 3 inches. The mower will shred the chitin, accelerating microbial decomposition in the thatch layer. According to turfgrass researchers at Purdue University, the minor aeration holes created by emerging nymphs actually benefit soil oxygenation, meaning your lawn will likely be thicker and healthier the following spring.
Frequently Asked Questions
Do cicadas bite or sting humans?
No. Cicadas lack the mouthparts to bite and do not possess stingers. Their proboscis is designed exclusively for piercing plant xylem to drink sap. If a cicada lands on you and attempts to probe your skin, it will feel like a mild pinch, but it cannot break human skin or transmit diseases.
Will systemic tree injections kill cicadas?
Systemic insecticides like Imidacloprid (e.g., Bayer Advanced 12 Month Tree and Shrub Protect) are highly ineffective against adult cicadas. Because adults feed minimally and primarily on the watery sap of twigs rather than the nutrient-rich phloem where the chemical concentrates, they rarely ingest a lethal dose. Save your money and use physical netting or contact sprays instead.
Why are there so many cicadas in my yard but none in my neighbor's?
Periodical cicada broods are mapped by historical soil conditions and root density from 13 or 17 years ago. If your yard had dense, healthy root systems (like mature oaks or maples) during the last emergence, the nymphs survived and multiplied. If your neighbor's yard was recently developed, heavily tilled, or lacked mature trees during the last cycle, the local nymph population starved or was destroyed, resulting in a localized dead zone for the current emergence.
