Frogs and toads lay eggs, commonly referred to as frogspawn, which once hatched produce a small amphibian called a tadpole that lives solely in water. Tadpoles are the larvae stage in the life cycle of frogs and toads, and they slowly metamorphosize into adult form by growing legs and losing their tails. Tadpoles are a common sight in garden ponds and can be killed in a variety of different ways.
The least intrusive or dangerous way of removing and killing tadpoles is to manually remove them using a fishing net. Use the net to remove all the tadpoles from the affected area of water and then they can be disposed of in a number of ways. Tadpoles can be fed to large fish, and will soon perish if left out in the sun or kept without any form of moisture for a prolonged time.
Hot Water Spray
Tadpoles do not react well to a sharp increase in temperature, and so an effective way of killing them is to use a hot water spray. Use a powerful spraying device containing water above 120 degrees Fahrenheit; the hotter the water the more effective it will be at killing the tadpoles. Spray the tadpoles in the water they live in continuously until they perish. This method is not particularly effective when dealing with tadpoles in large ponds because the tadpoles can relocate to a cooler area.
Chlorine is a very effective way of killing large numbers of tadpoles when manual removal and hot water spraying will be ineffective or too time consuming. Add chlorine to the pond or area of water that the tadpoles must be removed from and they will die quickly. The main problem with using chlorine that is will also kill any other life inside the pond, so relocating goldfish and any other pond life that is not the target must be done before the chlorine is administered.
According to the University of Pittsburgh, the widely used herbicide Roundup, manufactured by the agricultural biotechnology company Monsanto, contains a chemical that is deadly to tadpoles and frogs. After some tests it has been concluded that the chemical polyethoxylated tallowamine, used as a surfactant in the product, is responsible for killing the amphibians. Adding Roundup herbicide to water where tadpoles live is another effective way of killing them; however, the effect the herbicide will have on other life in the same water is not known.