You might try spraying the plants with Neem oil. It is a natural insecticide made from the oil of the Neem tree. Make sure you read the directions carefully and apply per the label (ie., don't spray when the sun is out, etc). Also check to see if certain plants shouldn't be sprayed.

Thanks a lot for the advice "Jenny in se pa"... today I read on the internet that spraying plants with strongly brewed coffee too might be of help in getting rid of a grasshopper... any idea if this might work??...

If the thought is that the caffeine in the coffee might kill them, you could try it. You would want to make sure that you don't get too much in the soil (try to keep it just on the leaves) as brewed coffee is relatively acidic and you don't want to unecessarily affect the pH of your soil.