For Tomato Horn Worms, the best defense are Cardinals. The Cardinal's
favorite food is horn worms. Their second favorate is Sun Flower Seeds. In
the spring keep your bird feeder stocked with sun flower seeds to attract
cardinals, and get them to stay in the area. Watching them hunt in you
'maters is fun tool

For Aphids, I use Ladybugs. You can buy them at a good garden shop or by
mail order.

For other pests, as a last resort, I use a product from "Gardens Alive"
called "Pyola". It's a mix of Canola Oil and pyrethrin, an extract from
Chrysantemum flowers.

Rich