This year is the first year that I have had any problem aphids and they have killed not only one chilli plant but also an eggplant (aubergine) plant. Unfortunately I believe they were on some chilli plants we were given as a gift but they soon spread. We also have some on our currants at the allotment but they do not do as much damage there. However you can see the red discolouration and pocked marked leaves that is the result of them.
Despite that they are a pain to remove there are quite a number of ways to remove them but depending on the location you might need to alter the technique.
One is to use a high pressure hose to blast them off (obviously for outdoors) or manually pick them off with your fingers.
Second is to use some eco-sprays to try and kill them.
Add 7.5 ml neem oil per 1 liter of water. If it has solidified you can place the container in some warm water so that it is fluid. Add some dish fluid to the mixture and then spray on your plants. (Do not use on plants that will be in direct sunlight just after spraying as it will burn your leaves!)
Crush some garlic cloves in water and once the water smells garlicky spray on plants adding some food oil can help but don’t use too much! Recept: 1 l vatten, 1,5-2% såpa, ipressad vitlök.
Or you can even add some garlic to your neem oil spray.
*Garlic oil is a non-selective insecticide, which means that it will kill beneficial insects (such as lady bugs, who are natural predators of aphids) just as easily as it kills the bad guys. It’s best to keep as many beneficials around as possible. This spray should only be used if you haven’t seen any beneficial bugs or if you are indoors.
Thirdly: Add some ladybugs/ladybeetles/ladybirds native to your area to the infected plants as they will happily chomp away on the aphids without destroying your plants. However from research it needs to be the larve that you need so it can be a bit tricky indoors.