China Aster Pests

Aphids

• Aphids generally feed in large colonies, producing honeydew, a sweet fluid that ants and other insects are attracted to and feed on. Aphids don't usually kill a healthy China aster, but infestations are harmful and unsightly. Check your plants at least twice a week, knocking off any aphids you find or spraying them off with water. Carefully check the undersides of the leaves. This is usually enough to keep aphid infestations at bay, but if more control is needed, spray the plant thoroughly with a ready-to-use insecticidal soap or neem oil spray. Repeat the treatment daily until the infestation is controlled.

Spider Mites

• Spider mites look like tiny, moving specks and cause yellow and stippled leaves. Like aphids, they usually don't cause significant damage except in large numbers. Use a spray of water to remove them from the plant, or for more serious infestations, spray the plant thoroughly with a ready-to-use insecticidal soap or neem oil sprayed daily until the mites are controlled. You may need a magnifying hand lens to see mites and their eggs.

Scale Insects

• Cottony cushion scale insects and black scale can affect China asters. Scales mainly cause damage by sucking the sap from leaves and stems, while the honeydew they produce frequently attracts sooty mold. Hand removal of scales is usually enough for China asters, but you can also apply ready-to-use neem oil, as with aphids and mites, if needed.

Whiteflies

• Whiteflies also damage China aster by sucking out fluids, resulting in yellowing and dying leaves. Whiteflies are difficult to control and no insecticides are effective for this pest. The best defense against whiteflies is prevention in the form of removing infested plants that can pass the pests to other plants from your garden. Promoting natural enemies of whiteflies, such as lacewings and some lady beetles, can also be helpful.

Caterpillars

• Foliage-feeding caterpillars are destructive, chewing holes in leaves and flowers, and sometimes eating entire plants. As with any pest, check your China asters regularly and handpick any caterpillars you find. Keep the area clear of weeds, which can harbor caterpillars that move onto other plants nearby.

Leafminers and Leafhoppers

• Leafminers are small, yellow and black flies that earn their name by mining leaves and petals to expose sap to feed on. Damage is rarely significant and usually requires no treatment. Keep your China asters looking their best by clipping of older infested foliage.

  Leafhoppers rarely require treatment because their damage is minimal. Their feeding can result in pale, brown or stippled foliage, but won't result in major plant damage.

Weevils

• Adult weevils feed on leaves, which become ragged, while their larvae feed on roots, causing more plant damage. You can handpick the adults and destroy them, but unfortunately there are no effective insecticides for the larvae. For heavily infested plants, your only option may be to destroy the aster to prevent the weevils from spreading to nearby plants.

Thrips

• Tiny thrips feed on plant fluids. Some thrips are beneficial because they feed on other pests, so only treat thrips when they are causing damage to your plant. A healthy China aster can probably tolerate some thrips feeding.

Chrysanthemum Lace Bug

• Lace bugs feed on plant sap, which results in stippled or bleached-looking leaves. Fortunately, this is another China aster pest that does little damage and doesn't need treatment. Keep your asters as generally healthy as possible and they should tolerate lace bugs easily.