Considering frogs and toads very much like mosquitos and mosquito larvae as a food source, what most likely happened in Kathy Durrum's situtaion is that by introducing mosquito dunks and killing the larvae they removed the food source for the frogs which caused a large number of them to starve to death. Removing the dunks allowed the mosquito population to proliferate which then also allowed the predators of mosquitos, frogs and toads, to also proliferate. Any time you remove or reduce the amount of an animal from an environment that is a small ecosystem you're doing damage to that entire system, not just the one specific animal in it.

The plant material deteriorating uses up essential nutrients so unless you feed the living plants a bit more than enough there wouldn't likely be enough for the duckweed. The only thing affected by mosquito dunks are mosquito larva and black flies.

Wilderness - when you say pets, what kind of pets are we discussing? Apparently Permethrin is very toxic to cats and fish, though not so much to other mammals. From Wiki: Permethrin acts as neurotoxin, slowing down the nervous system through binding to sodium channels. This action is negatively correlated to temperature, thus generally showing more acute effects on cold-blooded animals (insects, fish, frogs...) over warm-blooded animals (mammals and birds): * Permethrin is extremely toxic to fish and aquatic life in general, so extreme care must be taken when using products containing permethrin near water sources. * Permethrin is also highly toxic to cats and flea and tick repellent formulas intended and labeled for (the more resistant) dogs may contain permethrin and cause feline permethrin toxicosis in cats.[7] * Very high doses will have tangible neurotoxic effects on mammals and birds, including human beings. Permethrin does not present any notable genotoxicity or immunotoxicity in humans and farm animals. Permethrin is classified by the United States Environmental Protection Agency (EPA) a likely human carcinogen, based on reproducible studies in which mice fed permethrin developed liver and lung tumors.[8] Carcinogenic action in nasal mucosal cells for inhalation exposure is suspected due to observed genotoxicity in human tissue samples, and in rat livers the evidence of increased preneoplastic lesions lends concern over oral exposure.[9][10] Recent studies (Bloomquist et al., 2002) [11] have linked permethrin exposure to Parkinson's disease, including very small (per kg.) exposures: "Our studies have documented low-dose effects of permethrin, doses below one-one thousandth of a lethal dose for a mouse, with effects on those brain pathways involved in Parkinson's Disease [...] We have found effects consistent with a pre-parkinsonsian condition, but not yet full-blown parkinsonism." [12][13] Due to high toxicity for aquatic life, permethrin and permethrin-contaminated water should be properly disposed of. Degradation is quick and should the chemical be trashed far from any aquatic life, the negative effects would be minimized. Ideally, in a non-industrial context, the contaminant can be set in the light to induce photodegradation. Contaminated water set in direct sunlight exposure will be cleared of the permethrin and any known pollutant subproducts after a few hours. Recently, in South Africa, residues of permethrin were found in breast milk, together with DDT, in an area that experienced DDT treatment for malaria control, as well as the use of pyrethroids in small-scale agriculture.[14] I feel your pain with the midge; I believe I'm having some level of success with granular imidicloprid that I water in. I'm still finding maggoty tips here and there, but almost all of my roses are setting buds. Good luck! Lara Here is a link that might be useful: Full Wiki page

Well BT been around for a long time and the dunks take 2 weeks or more to work becuase the larvae have to eat the stuff.. if you live in mosquito country like I do I wont wait that long to get rid of the pests and the life threatning deseases they transmit.....The BT has been used here in vegatable gardening and is available in garden centers but not box stores