Paul Turner "Bug Farming"
Photos by Ian McCausland
Story By Ed Matlashewski
Appearing in the Ducks Unlimited Canada Conservator,
Volume 19, Number 1, 1998, p 14-15.
I t's a popular storyline in classic alien movies. An alien life-form arrives on Earth and proceeds to take over. It breeds quickly and has a voracious appetite, destroying everything in its path. Earth's defenses against the life-form are either pitifully non-existent or pose a danger to the entire biosphere. In one classic movie Was of the Worlds, the alien life-form is defeated by a virus - a tiny bug. In the war against purple loosestrife, tiny bugs may turn out to be real life heroes.
| Paul Turner "Bug Farming" |
Photos by Ian McCausland |
Purple loosestrife is an alien life-form in North America. The plant,
with its attractive purple blooms, landed on these shores over 100 years ago,
its seeds carried in the planking of ships. In the past century, it has advanced
across the continent, partly due to its persuasive beauty, and more importantly,
because North America has no natural defenses against the plant's onslaught.
While it can seem benign on dry land, purple loosestrife causes the
greatest damage in wetlands. No waterfowl will nest, no fish will survive and
no animal will graze or burrow in a wetland area dominated by purple loosestrife.
Not even insects will hang around.
"When purple loosestrife takes over a wetland area nothing else tend to live there," says Cory Lindgren who heads up the Manitoba Purple Loosestrife Project (MPLP), spearheaded by DUCKS UNLIMITED in cooperation with provincial and federal agencies. Purple loosestrife is so aggressive that it replaces all other plants in the wetland. It is the natural plant diversity in an ecosystem that is so important in attracting a variety of life. "There is no bird, mammal or fish in North America that feeds on the loosestrife," Lindgren added. "And chemical control of the plant may mean a lot of damage to the wetland environment."
The search for a solution took researchers to Europe where the plant
originated. There, purple loosestrife has a variety of enemies to keep it in
check. "When the research was first started, about 120 types of insects were
identified as living off purple loosestrife and then the number was narrowed
to five insects that live exclusively on loosestrife," explains Lindgren. That
biological control involves introducing a natural enemy that doesn't attack
native plants. 
The
Manitoba Purple Loosestrife Project has concentrated its efforts on two species-
a flower feeding beetle and a leaf-eating beetle. Efforts to find a biological
control are taking place across North America. Last summer, Lindgren and his
summer support staff raised insects and kept them inside pens made of netting.
The bugs were then released into purple loosestrife areas and closely monitored.
The early results are promising. Where the bug numbers were large enough, purple loosestrife took a beating. But Lindgren is not claiming victory. "It's going to take quit a few years of releases of insects for significant results to show," he says. "The goal is not eradication of loosestrife but to have some control over the spread. Hopefully in a few years a safe herbicide can be identified and the combination of the two can be effective."
The spread of purple loosestrife, also known as Lythrum or Morden Pink, has been aided by its beauty. Homeowners like the plant because it looks great and grows well in our climate. Seed from garden plants quickly escapes and spreads into nearby ditches, rivers and wetlands.
Features
Purple loosestrife grows three to six feet tall with several square, woody stalks
per plant. Its leaves have smooth edges and are attached directly to the stalk.
The flowers that appear from June to September are a pinkish/purple color.
Removal
The entire plant must be removed to minimize chances for regrowth. When digging
out the root mass, make sure all pieces have been removed. Roots can reach a
depth of one foot or more. Cutting, flooding or burning the plant where it stands
does little to stop it. The entire plant should be dug up and placed in a container
to completely dry out, preventing it from going spread around by wind. Once
purple loosestrife it totally dried, it can be burned where permitted, composed
or bagged for disposal. All attempts at removal should be done by mid-summer
before the plant goes to seed. Check the plant for seeds before removal. If
there are seeds visible and there's a chance of spreading them, put the project
on hold until next year. Where digging up the plant is not possible, removal
of the flower head will slow the spread of the plant.
Plant eating insects will not control loosestrife in all areas. Many communities and wildlife groups have organized loosestrife pulls. If you have a small population of purple loosestrife in your area, take action and organize your own loosestrife pull event.
