If you notice the presence of white worms in your flower bulbs or the surrounding area, you are certainly observing flowering bulb pests. However, the pests are not worms; they are soft-bodied adult insects or larvae that simply resemble white worms. Through consistent maintenance of your prized flower bulbs, you can cultivate vigorous plants with a greater capacity for avoiding and fighting off pest infestations and the resulting damage.
Aphids, commonly referred to as plant lice, typically populate the tips of new plant growth on bulbs. Though aphids are not white worms, they may resemble them with their small soft bodies that often take on an ovular or globular shape measuring approximately one-eighth to one-sixteenth of an inch in length. Aphids may display white marks or take on a whitish colour because of a waxy covering. These sucking bugs feed on tissue fluid and damage plants with their excretion of honeydew, a sugary, sticky substance. Honeydew attracts and encourages the development of sooty mould, a fungal disease that results in a black moldlike substance on the surfaces of your flowering bulb. Control aphids with the application of insecticidal soap for a botanical option that is less toxic than stronger chemical options such as malathion or cyfluthrin.
Narcissus Bulb Flies
The narcissus bulb fly (Merodon equestris) looks like a tiny bee in its adult stage, but as larvae, the flies look like white worms. Larvae are maggots with white or greyish yellow bodies. Narcissus bulb flies damage flower bulbs by burrowing into soft tissue and feeding on plant material. The infestation commonly leads to plant rot, destroying the bulb plant. Control this problem by gathering and destroying flies by hand or soaking the bulbs for 40 minutes in water heated to between 43.0 and 44.0 degrees Celsius, according to the Clemson University Extension.
Lesser Bulb Flies
Lesser bulb flies display deep metallic blue bodies in maturity, but as larvae they display bodies similar to narcissus bulb flies. The maggots resemble white worms with their white, yellow or grey bodies measuring one-sixteenth to three-eighths of an inch. These flies tunnel into your flowering bulbs and result in decay that turns soft tissue into a part-solid, part-liquid substance, according to the Clemson University Extension. Control lesser bulb flies and avoid plant death by following the same heated water treatment recommended for narcissus bulb flies -- but for three hours.