To make a long story short, a tree in my yard, a Dipterocarpus alatus   

Yang Na tree, is a gigantic tree here in Thailand has some big seed pods that fall in the early part of the year. It drop a few hundred seed pods every year. I am trying to get them to sprout for planting.

If you take the pod and put it in a tank of water for use on plants in the dry season, you will not get any mosquitoes in the tank. I have a few 100 gallon tanks that used to always get mosquitoes, but with the addition of just a few seed pods, no mosquitoes.

I have had an open tray of water holding the seeds for planting all summer, and not one mosquito or larva. I looks like the seed releases a tanin, as the water stains yellow-brown with a handful of seeds, so I would not suggest using it for pets.

The attached image of the seed pod is from Wikipedia.

Yang Na tree, I searched and found no such qualities from that tree or seeds.

On 7/17/2026 at 7:56 PM, Hummin said:

Yang Na tree, I searched and found no such qualities from that tree or seeds.

I love a challenge! 🙂

Several interconnected mechanisms explain why this occurs:

1. Leaching of Resinous Terpenes (Natural Larvicides)

Trees in the Dipterocarpaceae family are highly resinous. The pods, bark, and wood contain concentrated amounts of oleo-resins rich in volatile secondary metabolites, specifically sesquiterpenes and triterpenes (such as dipterocarpol).

When the pods are left in water, these lipophilic (fat-soluble) compounds slowly leach out. In botanical chemistry, these specific terpenes function as natural bio-insecticides. When mosquito larvae ingest the water or absorb these compounds through their cuticles, the molecules disrupt their cellular membranes and metabolic pathways, acting as a slow-release larvicide.

2. Tannin and Polyphenol Saturation

The woody, fibrous structure of the pod and its long aerodynamic wings contain a heavy load of tannins and polyphenols. As the pod breaks down, these compounds dissolve into the water, often tinting it a yellowish-brown colour.

• Nutritional starvation: High tannin concentrations bind to organic matter and inhibit the growth of the microbial biofilm (bacteria and microalgae) that mosquito larvae depend on for food.

• Digestive toxicity: Ingested tannins bind to the digestive enzymes inside the larval gut, preventing them from absorbing nutrients effectively, which retards their growth or proves fatal before they can pupate.

3. Disruption of Surface Tension

Mosquito larvae and pupae do not breathe underwater like fish; they must periodically hang upside down from the water's surface, using a specialized breathing tube called a siphon to pierce the surface film and access atmospheric air.

The oily, resinous components leached from the Dipterocarpus pods create a microscopic film across the water surface or subtly lower the water’s surface tension. This makes it difficult or impossible for the larvae to firmly anchor their siphons to the surface boundary layer, causing them to slip beneath the surface and drown.

4. Oviposition Deterrence (Chemical Signalling)

Female mosquitoes are highly selective when choosing a site to lay eggs, relying on olfactory cues to evaluate whether a water body will support their offspring. The aromatic compounds and altered chemical profile of a tank infused with Dipterocarpus resin act as a strong repellent signal, warning the female to seek cleaner, neutral water elsewhere.

A Note on Efficacy: While this method acts as an effective, low-cost traditional deterrent, its real-world success depends entirely on the ratio of pods to water volume. If the water tank is large and constantly replenished, the concentration of leached terpenes and tannins may dilute below the lethal threshold for the larvae, requiring regular replacement of the pods to maintain defensive potency.

I use the BTi

Quote Grok AI

(naturally occurring soil bacterium. It produces protein crystal toxins (δ-endotoxins, such as Cry and Cyt proteins) that target mosquito larvae (and some related dipterans like black flies or fungus gnats)

Hear, not tried Mosquito Dunks, seemed expensive to me.

My experience with flies, mosquitos is a multi faceted, persistent approach has virtually eliminated any around the house. It took about a month so Don't give up.

If you take the pod and put it in a tank of water for use on plants in the dry season, you will not get any mosquitoes in the tank.

If you put goldfish in tank, they will eat the mosquito larvae and you won't need any pods and the fish poop in the water is fertilizer, no pods needed.

You're welcome! 🤠

2 hours ago, SiSePuede419 said:

If you take the pod and put it in a tank of water for use on plants in the dry season, you will not get any mosquitoes in the tank.

If you put goldfish in tank, they will eat the mosquito larvae and you won't need any pods and the fish poop in the water is fertilizer, no pods needed.

Insects& Entomology

You're welcome! 🤠

One more animal to worry about then. No thanks. The tanks are covered, hence no light. The larva enter via downspouts after a rain. The tanks also get some sun, enough heat created to kill fish, but not the larva.