Calla lilies are perennial flowering bulbs that are often grown indoors since they don't need full sunlight to thrive. However, indoor conditions shelter insect pests such as aphids, thrips and mealy bugs from weather and natural predators.
Thrips are white sucking insect pests about the size and shape of a comma. Aphids are also sucking insects and come in several colours. Their eggs are almost always white, dash-sized things hiding on the underside of leaves. Mealy bugs are larger and have a cottony-white body.
Mealy bugs feed on calla lily bulbs, leaves and stems. Thrips feed mostly on the leaves and often fold a part of the leaf over themselves to hide from predators while they suck the nutrient juices from the plant. Aphids congregate near plant nodes, where leaf meets stem or around the buds and blooms. All three cause deformation of the part of the calla lily where they feed, and major infestations can dwarf the plant.
All three insects are soft-bodied. Use insecticidal soaps per label instructions to desiccate their bodies. Repeat as needed to reduce and eventually eradicate the population.