Aphids can be controlled with sprays of malathion, or Orthene.
Several caterpillars feed on linden. Have the insect identified then apply the appropriate chemical. Bacillus thuringiensis will not be effective against sawfly larvae. Fall webworm nests can be pruned out when still small.
Lace bugs cause discoloration of the leaves. The insects are found on the undersides of the leaves. Use Orthene or malathion when the insects are first seen then again in 10 days. Repeat applications may be needed in several weeks.
Spider mites cause leaves to become stippled and yellowed.