Fortunately, water gardens are relatively free of insect pests. Dragonflies and damselflies that patrol the skies above the pond eat many of the pests that might otherwise create problems. The lists of pests is small and one of them is the very creature we are creating our water gardens for - the koi. Water lillies are the prime targets of these pests.
Aphids: Although many gardeners
claim that aphids are attracted to
dying leaves they also appear on
healthy plants. Water plant aphids
look like black granules of dirt only
they move. The most common
procedure for removing theses
annoying bugs is to hose them off
into the water for the fish to eat,
but the bugs are quicker at climbing
back on the leaves than the fish are
at eating them. Probably the safest
remedy is an equal mixture of vegetable oil and water (with a dash of dishwashing detergent to emulsify the oil) and spray the mixture onto the aphids that are munching the leaves. The oily film disrupts water gas exchanges so absorb it off the water promptly.
moth larvae wrap
themselves in a protective
shelter of floating leaves
and feed on the water lilly
leaves, usually where the
leaf meets the stem. The
larvae can work their way
all the way down to the
rhizome. The easiest way
to control them is to pluck them off the leaves. You can also spray with Bacillus thuringienis products available at garden centers. These products contain harmless bacteria that parasitize the digestive system of caterpillars and grub, killing them.
Midges look like swarms
of gnats over and around
the pond in the early evening.
Their larvae are very small
and burrow within the surface
tissue of water lilly leaves.
Their damage looks much
like terrestrial leaf miner except that the tunnel rots all the way through. The only remedy is to remove the infested leaf.
Mosquitos pose a unique health problem and an uncontrolled still pond can make the problem worse for you and for your visitors. You can reduce the number of mosquitos by keeping all your water moving in your pond, populate the pond with fish that will eat larvae and talk with your local mosquito abatement people to ensure you can enjoy your pond into the evening hours.
In an effort to control the spread of diseases to humans mosquito abatement districts have been created. These districts will supply you with free gambusia fish to help you control the mosquito population in your pond. All you have to do is call the phone number of the district closest to you. Call from January to April and schedule a time for them to come out and analyze the needs of your pond and they will bring back the appropriate number of fish and stock your pond when it is safe for the fish.