Get rid pests on bog plant with NEEM OIL ?

[pimen]

I notice something , some of my black taro stalks are always falling down despite the leaf still black n fresh,
Then I realize hundreds of red coloured aphids like eating the stalks near the bulb and make several stalks falling down

N there's specific moth that always laying egg n their caterpillar always eat my black taro leafs BUT they didn't TOUCH pennyworth or anyothers plant... Just the taro... that is incredible but make me really mad at the same time...

So...
How to get rid this pests ?
Since basically bog filter style is the same with aquaponic, Iv done a research and found that neem oil product work best as the nature pesticide that safe for aqua culture
Has anyone had the experience with this neem oil / similiar nature product ?
How was the result ?

 

[addy1]

I have used neem oil on land plants years ago, it did wipe out a bad aphid problem I had.

Never tried on a bog plant.

Nice write up about it

http://www.discoverneem.com/neem-oil-insecticide.html

 

[MitchM]

It's generally not a good idea to use any oil, either plant or petroleum based, around a pond because the oil will form a sheen on the water surface that will restrict gas exchange.
Research which plants attract predatory insects that will eat the aphids and plant those around your pond.
Check with your local horticultural society for advice.