Plan ahead for pest-free tomatoes
Last year, my three tomato plants produced an average
amount of tomatoes. Then, in mid-season, to my horror, I sliced
open some tomatoes only to find little maggot-looking
The tomatoes were unblemished, so I don't know how these
little critters got in there.
Please help. These tomatoes were bought at a reputable
garden shop, planted in full sun and watered
I'm afraid to have home-grown tomatoes
What you probably saw was the larvae of a fly we call pepper
maggot, a native of eastern Canada and the U.S.. Once, it lived out
its life around the weed, horse nettle. When pepper and tomato
fields came to this region, the fly found it could live on these
relatives of horse nettle, too.
It never reached "major pest" status. Infestations of pepper
maggot are patchy. Even on farms with a history of this pest, just
one portion of a field or one field among many may be infested.
There may be no infestation at all some years. As further evidence
that this is not a pest we see much or expect to become a regular,
The flies spend winter as pupae (the fly equivalent of cocoons)
in the soil near the plant they preyed upon the previous year. They
usually emerge early in July. Within a week the flies have found
horse nettle, pepper, tomato or eggplant with fruits just 4/10 to
1-2/10 inches in diameter. They lay eggs just under the skin of
these fruits. The wound is tiny, the size of the fly's ovipositor
-- egg laying organ. Even later you might see only a depressed
dimple on the surface. Unlike other tomato insects, these maggots
develop and do their eating on the inside -- no need to chew their
The maggots eat for 2 to 3 weeks, then chew their way out and
drop into the soil to wait out the off season.
Preventing infestation can take several paths.
First and most important, clean up after any maggot problems.
Don't leave infested fruit laying around. Remove any nearby
horsenettle weeds. (It's not terribly common; I see it once every
You can cover the plants with fine netting such as floating row
cover during adult fly time from early July to early August. If you
didn't rotate your plantings, it's possible that flies may emerge
from soil at the base of a covered plant. In that case the cover
won't do any good.
You can buy HB predatory nematodes (from mail order companies
such as Gardens Alive) and in August add them to the soil in your
tomato patch. They destroy pupating larvae so any flies that
bothered your plants this year don't survive to repeat the
You can plant only late-bearing varieties of tomato. Flies lay
eggs only on the fruit, so if there is no fruit during July, there
will be no fly eggs.
You can spray the plants with Malathion during July, repeating
as directed on the label. Start spraying when you see the first
The adults are brightly colored yellow striped flies. There are
three yellow stripes down the back and the eyes are iridescent
green. (Go to www.hort.uconn.edu/ipm/veg/htms/catchfly.htm to see a
Or, try the do nothing, it's not likely to happen again
strategy. It may work, or maybe you'll invoke my dad's old saying,
"What's the problem? Cut it out or close your eyes and chew -- it's
a little extra protein is all."
More reports of plants lost or badly burned over
...redbud trees partially or completely killed and foxgloves
vanished, even from beds where they had been happily resident for
Green thumbs up
to those who say "How nice" or "We like to look at your garden"
to their gardening friends and neighbors. Simple attention like
that is a great stimulus to the gardener to work even harder.
Sometimes it's all the gardener needs to persevere in a trying
Green thumbs down
to the capriciousness of winter kill, to freeze dry evergreen
leaves and needles within inches of the ground but spare all those
maple seeds to become seedlings. Was my brain winter damaged, too,
that I took the leaves off those beds and left the ground layer
bare, ripe for sprouting?
Originally published 5/17/03