As feared, the monarch population has crashed this year.
The number of these large, orange-gold butterflies counted has been a fraction of what’s normal — less than 10 percent.
North America’s most famous migrating butterfly was about two months late to our region this summer, and much reduced in numbers. Late arrival meant even monarch-friendly wildlife gardens probably will produce only one generation of new monarchs instead of two or three.
Our first monarch arrived July 26, followed by one Aug. 11 and three on Aug. 16.
We started to see newly emerged monarchs in mid-September. If they managed to mate and lay eggs almost immediately, they might just squeeze in another small generation before October ends.
But the flowers to feed the butterflies are in retreat, and the milkweed that is the monarch caterpillar’s only food is old and tough now.
Judith Johnson, of North Beach Haven, noted the same decline in monarchs on Long Beach Island. A longtime monarch supporter, she is helping a local school establish a butterfly garden.
She emailed me a good tip on how to keep the milkweed in our garden appetizing and functional for the late monarchs.
“Early on, I snip the tops off young plants. That way they will product more shoots,” Johnson said. “Then later in summer, I cut some down to almost nothing (sparing some to produce seed pods). They then will come back as young tender plants for the later generations that fly south.”
This worked in our garden. We saw the monarch caterpillars preferred the younger, softer plants.
The number of butterflies counted so far by the Monarch Monitoring Project in Cape May is dismal. The project runs a 5-mile route three times a day in September and October, determining the average number of monarchs per hour seen each week.
In the fifth week (ending early October) this year, counters saw just 21 monarchs per hour. Same week last year the number was 442 per hour. Last year, the weekly rates added up to 1,009 through the fifth week. This year, it’s 72, barely 7 percent.
The numbers should improve in the second half of the count since the butterflies were so late arriving this year, but a record low overall count seems assured.
One factor in depressing monarch numbers this year was a cold, wet spring in Texas and other southern states where the butterflies first head north after wintering in Mexico. That will surely be better in the future.
But monarchs only covered 3 acres in their Mexican mountain “sanctuary” last winter, 60 percent less than the year before and a record low, says the World Wildlife Fund. Illegal logging has reduced the area available.
A bigger problem is the decimation of the monarch caterpillar’s food plant, milkweed, whose milky sap protects the caterpillars and butterflies by making them distasteful to birds.
Monarch Watch says 80 million acres of corn and soybean fields that used to have milkweed borders were rendered a butterfly dead zone by the use of herbicides that kill everything but the genetically modified crops. Ethanol from corn is driving the push to boost the crop.
Like other insects, monarchs can produce lots of offspring and recover quickly if habitat makes that possible.
Milkweed already had been eliminated from much of suburban America, so farmland was a last bastion. The monarch population crash might not be temporary this time.
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