Lesser Bulb Flies
DESCRIPTION OF THE PEST
Lesser bulb flies (Eumerus species)
range in size from 3/16 to 3/8 inch in length.
They are dark blue with a metallic bronze sheen. The larvae (maggots) range in
size from 1/16 to 3/8 inch and in color from white to grayish yellow.
Symptoms and damage
The maggots enter and then tunnel through the
bulb. The bulbs begin to decay and fill with a semi liquid material. They may
be killed outright or damaged so that only very small leaves are produced the
following year. The maggots survive the winter in the bulb and the following
spring they emerge into the soil where they pupate (transform to a nonfeeding
stage where the larva changes to an adult form). The adults emerge, mate and
the female crawls down through openings in the soil such as those left by
leaves as they die to lay eggs on or near bulbs as well as on the soil surface
and on the leaves at the neck of the bulb.
Cultural control of this pest includes mowing
leaves as soon as they dry in the spring. Lightly tilling the soil after mowing
destroys the soil openings that the adult females use to locate the bulb.
When bulbs are dug for dividing, any soft bulbs
should be destroyed. Treating slightly damaged bulbs by placing them in hot
water (109.4 °F to 111.2 °F) for 3 hours can control these pests. Be sure to
keep an eye on the temperature and not let it go over the recommended
temperature range as higher temperatures can damage the bulbs.