Summit BTI Granules - 8 lbs. per acre

The Collier Mosquito Control District (CMCD) carries on extensive spraying of Summit BTI Granules in Collier County residential areas.

Ave Maria	9/24/2025
Shaggy Cypress Swamp	10/6/2025
Shady Hollow Blvd E and Winchester Head Swamp areas	10/21/2025

For use in standing water where mosquito larvae occur.

Active Ingredient: Bacillus thuringiensis subsp. israelensis,

Strain SUM-6218.

The active ingredient in Summit BTI products (like Briquets, Dunks, Granules) is Bacillus thuringiensis subspecies israelensis (Bti), specifically strain SUM-6218 or BMP 144, which contains bacterial solids, spores, and insecticidal toxins that target and kill mosquito larvae but are safe for other wildlife like fish, frogs, and pets. The concentration varies by product (e.g., ~2.86% for granules, ~10.31% for briquets), with the rest being inert ingredients, but all rely on Bti to provide long-lasting mosquito control. 

Key Details:

• Active Ingredient: Bacillus thuringiensis subspecies israelensis (Bti).

• Mechanism: A naturally occurring bacterium that larvae ingest, killing them before they become biting adults.

• Forms: Available as slow-release briquets (Dunks), granules, or chunks that float on water.

• Safety: Harmless to humans, pets, fish, birds, and beneficial insects, making it an environmentally friendly choice.

• Other Ingredients: Mostly inert carriers and binders (like cork matrix) that allow for sustained release. 

  Summit BTI (Bacillus thuringiensis israelensis) is considered very low-risk for human health by agencies like the EPA; it targets mosquito larvae specifically, but direct contact might cause mild skin or eye irritation, requiring basic precautions like washing hands and wearing safety glasses, with rare allergic reactions possible from repeated high exposure, though no long-term issues like cancer or genetic damage are linked to BTI. 

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  Key Health Risk Information:

  • Low Toxicity to Humans & Pets: BTI toxins only activate in the alkaline gut of insect larvae, not in humans or mammals.

  • No Serious Long-Term Effects: Studies show BTI doesn't cause cancer, genetic mutations, or birth defects in humans.

  • Potential for Minor Irritation: Direct contact, especially with concentrated forms, can cause temporary skin or eye irritation.

  • Allergic Reactions: Very rare cases of allergic sensitization from repeated exposure to high concentrations of microbial proteins have been reported, notes a safety data sheet from Summit Chemical. 

• Summit BTI granules, such as Mosquito Bits, are generally considered safe for wildlife when used as directed. The active ingredient is Bacillus thuringiensis israelensis (BTI), a naturally occurring soil bacterium that produces toxins specifically targeting the digestive systems of certain fly larvae. 

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  Direct Effects on Wildlife

  BTI is highly selective and has almost no direct toxicity to non-target organisms because most animals lack the specific gut pH and receptors required to activate the toxin. 

  • Mammals and Pets: Non-toxic to dogs, cats, horses, livestock, and humans even if the treated water is consumed.

  • Birds: Harmless to birds that drink or bathe in treated water, such as those visiting birdbaths.

  • Fish and Aquatic Life: Safe for fish (including koi and goldfish), frogs, turtles, and shrimp.

  • Beneficial Insects: Does not harm bees, butterflies, dragonflies, or predatory beetles. 

  Target Species

  The granules are designed to kill only the larval stages of: 

  • Mosquitoes

  • Black flies

  • Fungus gnats 

  Indirect (Trophic) Effects

  While BTI is not directly poisonous to most wildlife, repeated or large-scale use can have indirect "knock-on" effects on the ecosystem by reducing the food supply for insect-eating animals. 

  • Food Web Disruption: Some studies have shown that intensive BTI spraying can lead to a decrease in the reproductive success of birds (like house martins) because there are fewer midges and mosquitoes for them to eat.

  • Impact on Predators: Predators such as dragonflies and newts may be indirectly affected if their primary prey (larvae) is eliminated from the environment. 

  Usage Safety

  • Application: Granules can be used in fish ponds, birdbaths, rain barrels, and animal troughs.

  • Restriction: They should not be applied to finished drinking water reservoirs intended for human consumption.

  • Shelf Life: Effectiveness typically lasts 7 to 14 days for granules, after which they must be reapplied.