Tomatoes have many pests that it would be hard to list them all. I will go over the main pests that a majority of people will see and how to combat them.
Aphids (Myzus persicae & Macrosiphum euphorbiae):
Identification: Aphids have tiny soft pear-shaped bodies with long legs and antennae. For tomato plants, the aphids can be green, or red. With a pair of tubelike structures calledcorniclesprojecting backward out of the hind end of their body makes identifying them easy. Aphids often feed indense groupson leaves or stems. Most aphids are not easily disturbed or removable.
Plan of Attack:
Nonchemical control is better because most insecticides will destroy beneficial insect as well.
Check your plants at least twice a week in order to catch infestations early. At this stage, you can hose them off or prune them out.
Aphids cause the greatest damage when temperatures are between 65°-80°F.
Ants are often associated with aphid populations since they are a food source, ants ward off many predators and parasites of aphids. Managing ants is a key component of aphid management.