You might want to try to identify the little black bugs, then find out what less toxic solutions might be to control them. This is from Wikipedia, on the subject of Sevin, which is a brand name for carbaryl:
Carbaryl kills both targeted (e.g. malaria-carrying mosquitos) and beneficial insects (e.g. honeybees), as well as crustaceans.
Although approved for more than 100 crops in the US, carbaryl is illegal in several countries, including the United Kingdom, Austria, Denmark, Sweden, Germany, and Angola.[3]
[edit] Safety
Carbaryl is a cholinesterase inhibitor and is toxic to humans. It is classified as a likely human carcinogen by the United States Environmental Protection Agency (EPA.)[4] (End quote)
When a pesticide is banned in other countries, there's usually a good reason. Which plants are they on? What are you growing? Most harmful garden pests are pretty specific about which plants they eat. For example, potato beetles are gonna stick to the potatoes, tomato hornworms are going to be on the tomatoes, etc. There are exceptions, (like aphids, that eat all kinds of stuff) but if a particular bug is all over everything, it's a usually a predator, eating the pest species.
So it's very helpful to find out what bug you're seeing, and go from there. It may be eating the things that are eating the leaves.