Stink bug
Symptoms
A flat, shield-shaped brown or green insect that emits an unpleasant odor when disturbed. It only attacks fruits, preferring green ones. It punctures the skin and sucks the juices, leaving sunken, colorless spots.
Control and prevention
Garlic infusion.
Related problems
Similar symptoms might indicate a different cause — compare them.
Aphids
These are small green (sometimes reddish, brown) flies that usually attack in swarms. They suck the sap from leaves or stems, but do not touch the fruits. A tomato plant can withstand significant aphid attacks, but they should not be neglected, as too many can weaken the plant. These flies can also be carriers of viral diseases. A similar species is whiteflies; they act similarly, but are half the size. Aphids are protected by ants: contrary to popular belief, ants do not destroy aphids, but help them thrive.
Spider mites
A creature the size of a salt crystal with two black spots on its back. They usually weave webs on the underside of the leaf, causing the most problems during the hottest and driest summer months. They suck plant sap — yellow spots develop in the affected areas, which later turn brown and die.
Bacterial canker
Quite rare, but if it attacks, it can destroy the entire season's harvest. The main symptoms are wilting, curling, and browning of leaves. Initially, not the entire leaf wilts, only a part of it. Even if the plant is infected at the seed stage, symptoms may not appear until flowering. Later, spots with a double border appear on the fruits. The disease spreads rapidly — infected plants must be removed immediately.