Duplex-G - 6 lb./acre

Granular

Duplex-G  Bti

The Collier Mosquito Control District (CMCD) carries on extensive spraying of Duplex-G in Collier County residential areas.

Ave Maria	6/25/2025
Fiddler's Creek	6/27/2025
Sabal Bay	6/27/2025
Verona Walk	7/1/2025
Livingston Road and Veterans Boulevard	7/11/2025
Orange Blossom area	7/25/2025
Immokalee and the Hacienda Lakes community.	8/6/2025
Winding Cypress	9/2/2025

Duplex-G is a bacterial larvicide that targets mosquito larvae. This product is effective for 14-28 days. This is another granular larvicide. EPA -ACTIVE INGREDIENTS Bacillus thuringiensis subspecies israelensis Strain BMP 144 solids, spores, and insecticidal toxins* 5.35% (S)-Methoprene (CAS # 65733-16-6) 1.60% OTHER INGREDIENTS Reg. No. 89459-93.

Duplex-G is not considered dangerous to humans when used according to the product label's directions. Its active ingredients have low toxicity to mammals like humans, but direct exposure should still be avoided. 

Active ingredients and their safety

Duplex-G uses two main ingredients to target mosquitoes at different life stages. 

• Bacillus thuringiensis subspecies israelensis (Bti): A naturally occurring soil bacterium, Bti is specifically toxic to mosquito larvae and black flies. When mosquito larvae eat the Bti, the bacterium produces a toxin that destroys their digestive system. Because this mechanism is specific to certain insects and requires an alkaline gut, it has no toxic effect on humans, pets, birds, or fish.

• (S)-Methoprene: This is an insect growth regulator (IGR) that mimics a juvenile hormone, preventing mosquito larvae from developing into biting, breeding adults. The U.S. Environmental Protection Agency (EPA) has found methoprene to be of low toxicity and to pose very little risk to people. 

  
  

Safety precautions and risks

Despite its low toxicity, there are still risks associated with direct exposure and certain individuals may be more sensitive to the product. 

• Eye and skin irritation: The product label warns that Duplex-G can cause moderate eye irritation and that skin irritation may occur with direct contact. Protective equipment like eyewear and waterproof gloves is recommended for applicators.

• Respiratory irritation: The Safety Data Sheet (SDS) warns that inhaling dust from the product can cause respiratory irritation. Repeated exposure to high concentrations of microbial proteins in the product may also cause allergic sensitization in some individuals. A respirator is required for certain applications.

• Environmental hazards: Methoprene is known to be toxic to some aquatic invertebrates, particularly in estuarine and marine environments, which is why product labels include specific warnings.

• Inert ingredients: While the active ingredients have been thoroughly tested, the inert ingredients in any pesticide are not subject to the same stringent testing. Certain individuals may be sensitive to these other components. 

  
  

Duplex-G, a larvicide containing the insect growth regulator (S)-methoprene, poses a significant danger to dragonfly larvae by disrupting their normal maturation process. While its other active ingredient, Bacillus thuringiensis subspecies israelensis (Bti), is relatively safe for dragonflies, the methoprene component interferes with the development of all arthropods, which includes dragonflies. 

Reference

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Protecting dragonflies and other beneficial insects

Dragonflies are important natural predators of mosquitoes and play a key role in a healthy ecosystem. When using mosquito control products, consider the following to protect non-target insects: 

• Opt for Bti-only products: If you need to treat standing water for mosquitoes, use a product that contains only Bti, such as a mosquito "dunk." Bti is highly specific to fly larvae and is harmless to dragonfly larvae, fish, and other aquatic life.

• Remove standing water: The most effective method for controlling mosquitoes is to eliminate their breeding sites. Drain or empty any containers that hold stagnant water on your property.

• Support healthy habitat: Creating a wildlife-friendly aquatic environment with native plants can attract dragonflies and other natural predators that help control mosquito populations without the need for chemical intervention. 

  
  

Another interesting fact is that dragonfly nymph molt up to fifteen times before reaching the adult stage, and this is why methoprene and other pesticides are so deadly to them.

Reference

https://www.dragonflyday.org/about.html#:~:text=Another%20interesting%20fact%20is%20that,are%20so%20deadly%20to%20them.