This year there was a good arrival of frog spawn in the garden pond and a good development of tadpoles. In midsummer, however, as they begin to lose their tails and gain legs their numbers reduce and there are now very few to be seen. This pattern has occurred over the past two to three years. Prior to that they could be seen at this time of year as tiny frogs congregating around the edge of the pond in large numbers. The pond has a sludgy bottom and oxygenating plants. Any action required?N.P. Delaney, Dun Laoghaire, Co. DublinIt is likely that in the past two or three yeas a great diving beetle or two, or perhaps a pair of newts, entered the pond and feasted on them - and they have also been eating each other. There is nothing you can do about either; it is a natural ecological process. Plants in the pond give the tadpoles a place to hide, but they also provide shelter for predators.Edited by Michael Viney who welcomes observations sent to him at Thallabawn, Carrowniskey PO, Westport, Co. Mayo.