So if your garden is not full of harmful insects, it won't support large numbers of beneficial ones. It is best to strive for a balance of low levels of both harmful and good insects. Don't overlook handpicking and destroying insect pests. In addition, some insects may respond to traps, baits, or sticky cards placed in or near the garden. Too much nitrogen promotes vegetative growth and stimulates an increase in aphid and mite populations.
Most natural enemies do better with a diversity of hosts or plants.
Annual or perennial flowering plants provide an alternative food source of pollen and nectar for many beneficial insects such as syrphid flies, robber flies, lady beetles and parasitoid wasps. They can also provide shelter and humidity. Employ cultural practices. Trap cropping may attract a pest away from the desired plant but toward a plant that is not important in the garden. Appropriately timed applications of pesticides may then be applied to the trap plant.