In a vivarium, wabi-kusa or in open aquariums water plants can thrive excellently in their emerse form. A sudden infestation with pests such as aphids can be quite annoying and may cause massive losses in plants. Here are some countermeasures that can be taken without the use of chemicals.

Control measures

The Dip

If you have a classic wabi-kusa, meaning small balls of soil wrapped in thread, you may want to try a dip. The wabi-kusa is submerged completely in a correspondingly high vessel for several hours. Keep in mind that the soil balls should have enough thread wrapped around them to ensure they survive some time underwater.
The plants do not mind being submerged for a while. However, most pests such as aphids will not survive this procedure. They’ll let go at some point and float (dead) to the surface. Of course, they’ll have to be removed before the wabi-kusa is taken out of the water bath. If necessary, this measure can and should be repeated several times.

Nettle water

For larger wabi-kusas or structures that do not allow for a water bath, you may want to choose a different biological control method. For this, a brew is made from ordinary nettles. Put about 100 g of nettles into 1 liter of water, let it boil for a few minutes and let rest for a day. After 24 hours, the nettle water is filled into a small spray bottle, which you use for fogging the infested plants. The nettle water will fight the pests but won’t harm the plants or accumulate in the soil. The procedure should be repeated a few times to kill off freshly hatched aphids.

Note: In our practical test, this measure unfortunately hasn’t proven to be particularly effective. Although we saw a slight decrease in aphids, other methods such as the aforementioned dips were much more effective.

Ladybugs

Ladybugs and especially their larvae are excellent natural predators of aphids. A mild temperature (at least 15 °) and some sunlight provided, these little fellas can also be used indoors. In garden supply stores, ladybug eggs can be purchased for pest control. These eggs are placed on affected areas together with some sort of carrier substrate. After a few days, the first hungry, hungry larvae will hatch and gradually eradicate the aphids.
Attention: The plants should be kept free from ants. Ants will defend the aphids and attack ladybug larvae.