and Agri-Food Canada Insect Identification Sheet No. 99
and Beet Leaf Miner
Two species occur in Canada, P. hyoscyami (Panzer)
and P. betae (Curtis), distinguishable from each other
only by minute differences, mainly in the genital structures. Both
introduced from Europe before 1880, and now are generally distributed
throughout North America.
damage spinach, beets, chard and related plants by mining between
the upper and lower leaf surfaces. They render leaf crops unfit
as food and stunt root crops. Most damage is noticed late in
the growing season.
Life History, Appearance and Habits:
The insect overwinters in the puparium in the soil. In April and
May, the greyish, slender-bodied, black-haired flies appear in
the fields. They are about 7 mm long. The females deposit small
white eggs, singly or in one to five parallel rows on the undersurfaces
of leaves. After hatching, the tiny maggots eat slender mines which
expand into leaf blotches as the larvae increase in size. Mines
of a number of larvae join to form larger blotches. When mature,
larvae drop to the ground and pupate in the soil. There may be
three or more generations each year.
Early in spring,
plow the susceptible field deeply to expose the overwintering
pupae to environmental stresses. Destroy susceptible weeds, such
as lamb's quarters and nightshade, as well as old crop remnants.
In small plots, screen-covered frames can protect small plants
of the host crop from egglaying flies. For information on control,
consult your provincial Department of Agriculture.
THE FOLLOWING (UNTIL OTHERWISE NOTED) IS FROM: GERBER, H.S. 1983.
MAJOR INSECT AND ALLIED PESTS OF VEGETABLES IN BRITISH COLUMBIA.
MINISTRY OF AGRICULTURE AND FOOD.
Spinach Leaf Miner:
Pegomya hyoscyami (Panzer) Leaf miners form conspicuous silvery
blotches on the foliage. This species also attacks weeds, including
lamb's quarters, chickweed and nightshade.
blotches with a silvery overcast are formed by the larvae mining
between the surfaces of the leaves. This makes bunched beets
unmarketable. Heavy infestations stunt growth.
is a slender grey fly 4 mm long. They are frequently seen hovering
over the host plants. Small green or white maggots feed inside
the leaves, forming blotches.
several generations a year; pupae overwinter in the soil. Flies
lay eggs on the undersides of the leaves. Larvae enter the leaves,
feed until mature, then drop to the ground, pupate, and emerge
should be applied when mining damage is first observed. Two or
three treatments at 10-day intervals may be needed. Early in
the season infestations may be suppressed by destroying infested
crop residues and weeds.