Pansies are beautiful, lightly scented plants that grow to heights of 6 to 10 inches and appear in a tremendous variety of colours. They spread quickly and do well in cool weather, when natural predators are least active. Pansies attract a variety of pests that infest them, some of which are difficult to detect until the damage is already done. Keeping pansies free of pests is not always an easy task but is one that is well worth the effort.
Aphids grow in size from 1/16 to 3/8 inch and appear in colours such as tan, green, pink and black. Aphids are most prevalent in temperate zones and feed on the stems and new leaves of pansies. The waste produced by aphids as they feed is called honeydew because it is a sweet, sticky substance. Honeydew provides a food source for dark sooty fungus, which detracts from the beauty of the pansies. Ladybug beetles, available online or at plant stores, feed on aphids as do parasitic wasps and lacewings. If aphids cannot be controlled by natural predators, the use of insecticidal soap, instead of insecticides, is recommended.
Spider mites are extremely hard to identify on pansy plants. Spider mites are so small they are very difficult to see. The effects of their presence are also hard to spot but include very fine webbing on the plant. Tiny, pinprick holes appearing in the leaves with tan spots developing on them are early indicators of infestation. When seriously infected, the leaves may turn tan and die. Cool weather retards infestations of spider mites. Using insecticidal soap according to package directions is an effective treatment.
Slugs and Snails
Slugs and snails are molluscs and they need to continuously remain moist. As a result, they feed during the night, hiding out during the day under moist organic matter in the lawn and under flower pots. They leave a slimy mucous trail and large holes in the flowers and leaves of the plant as evidence of their presence. Control slugs and snails by keeping the soil of the garden area free of organic matter depriving them of their moist hideout.
The slugs and snails feed after dark and that is the best time to use a flashligh/torch to hand-pick them from the plants. Water the garden in the afternoon before beginning the hand-picking exercise to encourage the appearance of slugs and snails. Place a board in the garden, propped up to about one inch off the ground and moistened underneath. In the morning, lift the board and remove the snails and slugs. Diatomaceous earth, sprinkled around the base of the plants, is effective against slugs and snails because it has sharp edges that cut the soft bodies of the molluscs. The molluscs then die of dehydration.