Lacebug—Insect that is particularly bad on pyracantha.
Ladybug—Also called ladybird beetle. The best friendly insect that feeds on aphids and other small insect pests.
Lava Sand—Natural volcanic soil amendment used to increase the energy and the water-holding ability of the soil.
Leafhopper—Small insect with piercing-sucking mouthparts. These pests usually suck plant juices from the undersides of leaves.
Leaf miners—The larvae of various kinds of moths, midges, and flies. They feed inside the plant between the leaf surfaces and create serpentine trails or ugly blotches on the leaf.
Loam—Soil consisting of sand and light clay particles. Usually fairly big in organic material.