Like many indoor plants, Ficus lyrata or fiddle leaf fig hails from the tropics. In its natural habitat, this large-leaved tree can grow to 50 feet tall, but indoors it is pruned and valued for its dark green fiddle-shaped leaves. Fiddle leaf figs are bothered by relatively few problems, but they are susceptible to scale, an insect that can brown spots on leaves and deposit honeydew that can serve as a breeding ground for sooty mold.
The family of houseplants that includes the fiddle leaf fig in encompasses such favorites as the Indian rubber tree, weeping fig and laurel fig. Fiddle leaf and its cousins are part of a large family of tropical plants widely used for plant-scaping in malls and offices. They will tolerate drought as long as they have medium light levels.
The insect known as scale lives a sedentary life; it hatches and crawls out on a branch or leaf, finds a place and stays there for life, sucking carbohydrates and food out of the plant. Unless a scale population is very large, the only evidence of its presence will be brown spots where it feeds on a leaf or tiny bumps composed of molted coverings and wax called "test" of the armored scale. Soft brown scales have no armor, but they produce the sticky substance honeydew.
Scales are often brought into the home by ficus that have been raised in greenhouses and nurseries where scale goes unnoticed because the insects' natural camouflage and inactivity allows them to fade into the background of stems and branches. Once in the home, the scales have the benefit of a controlled environment---no rainstorms or heatwaves to control their propagation.
Scale attacks on fiddle leaf houseplants generally do not endanger the entire plant but do damage the appearance of its long, violin-shaped leaves. They are most vulnerable when in the nymph "crawler" stage but their 65-day life cycle makes control of a large-scale infestation difficult because generations begin to overlap.
Early detection of scales makes removal with tweezers or with a soft brush and soapy water a practical treatment. Another method of removal uses a "mini-swab" made with a toothpick and a bit of cotton ball fabric dipped in alcohol to stun the insects while they are removed from the leaf. Heavily damaged branches can be removed during regular pruning. Insecticidal soap and horticultural oils also work on the big leaves. Indoor insecticides do the most damage when scales are in the crawler stage; they must be used repeatedly to kill succeeding generations.