Lemon trees can easily become infested with insects, and getting rid of these insects can be easy or difficult, depending on the type of pest you're dealing with. Your lemon tree is most susceptible to attacks by insects such as mites, brown soft scales, citrus thrips and whiteflies, and aphids. Orangedog caterpillars and snails can also create serious problems in your lemon tree. To control these lemon tree pests, you must use either a miticide, an insecticide, horticultural and dormant oils, Bacillus thuringiensis or an insecticidal soap.
Get rid of citrus bud mites and citrus red mites on your lemon tree by spraying the tree with a miticide during the summer months. Spray all the foliage on the tree according to the directions on the label.
Spray your lemon tree thoroughly with horticultural oil in early spring to control brown soft scale insects. In spring or mid-summer, when the scale insects are moving around and in the "crawler" stage, spray the lemon tree with an appropriate insecticide. Spray the lemon tree with a dormant horticultural oil in late winter to kill any over-wintering scale insects.
Control citrus thrips and Orangedog caterpillars by spraying your lemon tree's foliage in early spring with a bacterial product, such as Bacillus thuringiensis (BTK). Spray your lemon tree again two or three times, every one or two weeks.
Get rid of citrus whiteflies on your lemon tree by spraying the tree with an appropriate insecticide. You may need to spray the lemon tree three or four times throughout the spring and summer to control the citrus whitefly infestation.
Spray the leaves of your lemon tree with an insecticidal soap in early summer to get rid of aphids. Apply the insecticidal soap to the leaves again in mid- to late summer if the aphids persist. If your lemon tree has a heavier aphid infestation, spray the undersides of the tree's leaves and all other areas where the aphids are visible with an approved insecticidal spray.