Bugs on rosemary plants pose a threat to the plant's health. Unattended to, the bugs may spread to other plants in the garden or invade the home when harvesting. Identify and eliminate bugs common to rosemary plants to keep the plants healthy.
The most common bugs that harm rosemary plants are aphids, spider mites, whiteflies and mealybugs. Ladybirds are particularly beneficial around rosemary plants, as they feed on the aphids.
An increase in beneficial insects is one indication that harmful bugs may be attacking the rosemary plants. Check the plants for signs of bugs, many of which are visible, particularly on the stems, under leaves and at the base of the plant. Examine the rosemary for dead or brown leaves and stems, another sign that bugs are eating the plant.
Spray the bugs with insecticidal soap or a solution of 1 cup water, 1/2 tsp dish soap and 1/2 tsp vegetable oil. Thoroughly rinse the plants off after the bugs die. Immediately trim and remove all dead leaves and stems to prevent reinfestation.