Aphids
Aphids are probably the biggest pests of all plant lovers. Depending on the weather, aphids multiply like an epidemic. With their proboscis they suck the plant sap directly from the plant's vascular system through the cells. The leaves bend and curl so that the shoots wither.
Here I point out once again the symbiosis with the ants. Aphids feed mainly on carbohydrate-rich plant juices. In order to cover their protein requirements, they have to consume far more carbohydrates than they need. The surplus is excreted as honeydew and serves as food for the ants. These provide the aphids with protection against other insects.
The most effective aphid control insects are the ladybug and its larvae and the lacewing. They are so effective that they are commercially available as eggs or larvae. But the gall midge, the ichneumon wasp and the flower bug should also be mentioned here.
Achieving high humidity levels should counteract the development of aphids.