We finally had to know.
Just what the heck is a bagworm?
Reports about the pesky insect have been popping up in the garden calendar for the past few months, until being overshadowed by calls about the ever-ravenous Japanese beetle.
While those beetles have been turning plants’ leaves into doilies, the bagworm has quietly been doing its thing, which is eating the needles on your evergreen trees and shrubs. Spruce, junipers and pines are particularly vulnerable.
“We are most concerned about evergreen trees because they don’t reneedle,’’ says Scott Evans, the horticulture program coordinator for the Nebraska Extension in Douglas and Sarpy Counties.
“Once those needles get chewed off, those don’t grow back.’’
The destructive caterpillar lives in a bag made of silk and fragments of needles or leaves. Its head and legs stick out as it feeds.
Males turn into ashy-black moths with transparent wings in late August or early September. That’s when they somehow impregnate the female in her bag, which she never leaves.
Sign up for The World-Herald's afternoon updates
Receive a summary of the day’s popular and trending stories from Omaha.com.
“I don’t understand how that happens, and they are very successful,’’ Evans said.
After overwintering in the bag, eggs hatch in mid-May to early June. The larvae parachute out of the bag onto neighboring trees and the cycle starts again.
They don’t limit their appetite to evergreens; any hardwood tree will do.
“But we are not concerned about those trees. They will refoliate next year,’’ Evans said. “They are fine.’’
Trees such as the Colorado spruce are hugely popular in this area, Evans said. People love the color and the similarity to a Christmas tree. But bagworms are fond of them, too, and can kill them if there’s a heavy infestation.
Watch out for browning needles.
To help save the spruces, junipers and pines, it’s best to treat for the worms when they are small. Bacillus thuringiensis and Spinosad are good options with little side effects for other insects. But now that they are larger, your options have changed.
“Bifenthrin and other more traditional products will be the products of choice along with hand-picking and dropping in a bucket of soapy water,’’ Evans said.
The bags need to be open and the caterpillars feeding for insecticides to work. Once the bags are closed, insecticides will not penetrate the bags to kill them.
Another option is to surround vulnerable trees with plants that attract bagworm predators. Asters and daisies are good options as well as fruit and seed-bearing plants that attract birds, which eat the bagworms in late summer.
It’s been an average year for bagworms, just as it’s been for Japanese beetles and june bugs, another topic for callers to the extension office. But that doesn’t mean it’s a good year.
All three bugs have taken their toll on trees, shrubs and plants.
“Every year I keep saying this; I feel like a broken record,’’ Evans said. “This was a tough year. Every year there is a different insect or disease we are trying to manage.’’
Cait Coughey of The Big Garden and Joey Vickery of the Omaha Public Schools will explore the many benefits a natural, outdoor learning environment can foster. If you’re interested in building a new school garden or outdoor classroom, they’ll guide you through the basics.
- A free first Thursday brownbag on herbs will be held at noon Aug. 1 at the Jayne Snyder Trail Center, 228 N. 21st St. in Lincoln. This all-things-green series is sponsored by Nebraska Statewide Arboretum, UNL Institute of Agriculture and Natural Resources, Lincoln Parks & Recreation and the Lincoln Downtown Association.
Jill Kuhel and Sharon Ohmberger will share their knowledge in “the glorious bounty of herbs’’ seminar. Email email@example.com with questions.
1 of 90
Rain clouds and a bit of a rainbow roll over the Millard, Nebraska, sky on Aug. 16, 2016.
The sun sets behind a center pivot located north of Red Cloud, Nebraska, on Thursday, July 27, 2006.
Storm clouds hide the sun as it sets over Nebraska's Sand Hills on July 7, 2009, near Thedord, Nebraska.
A summer storm passes north of Rose, Nebraska, on Sunday, June 10, 2007.
A rainbow forms over U.S. Highway 12, just east of Valentine, Nebraska, as storms roll over the area on July 25, 2017.
The sun sets behind an approaching storm as a car heads west on U.S. Highway 34 near Union, Nebraska, on April 24, 2016.
Icicles form on vines in downtown Omaha on Feb. 24, 2017.
Railroad tracks are illuminated by the setting sun on May 3, 2017, east of Scottsbluff, Nebraska.
The sun sets behind Chimney Rock on May 3, 2017.
Members of the Boats, Bikes, Boots & Brews group head to shore as the sun sets after an evening out on Lake Zorinsky on April 22, 2015.
Icicles hang from the horse carriage parking sign in the Old Market on Jan. 15, 2017.
Wheat, ready for the combine, is silhouetted by the setting sun as the wheat harvest on the Lagler farm near Grant, Nebraska, was in full swing on July 7, 2005.
A layer of fog covers the Missouri River near the Bob Kerrey Pedestrian Bridge on Feb. 5, 2015.
A setting sun creates a pink haze on a windmill and the Sand Hills southwest of Rushville, Nebraska, on Sept. 22, 2007.
Pigeons scatter at sunset as the St. John's steeple is silhouetted against the Woodmen tower in downtown Omaha on Oct. 3, 2014.
The sun bursts behind the clouds over the North Platte River east of Bridgeport, Nebraska, on July 26, 2006.
Steve Jobman, a farmer south of Minatare, Nebraska, cuts alfalfa after sunset on June 2, 2004.
Wheat waves in the wind in a field west of Dalton, Nebraska, on July 18, 2001.
The moon rises over the northern cross of the St. Cecilia Cathedral in Omaha on Feb. 10, 2017. On this night, there was a full moon, a lunar eclipse and comet 45P passed by the earth.
As the wind speed picks up, a woman holds onto her hood while crossing 16th Street along Dodge Street in Omaha on Feb. 24, 2017.
From left: Melody Borcherding, Kseniya Burgoon and Michael Beltz scoop out a vehicle on Jan. 23, 2018, in Norfolk.
Jeff Bachman harvests soybeans and prepares to transfer them as the sun sets on a field near Ayr, Nebraska, on Oct. 19, 2008.
As the sun sets, sandhill cranes arrive to roost in the Platte River at the Rowe Sanctuary & Iain Nicholson Audubon Center south of Gibbon, Nebraska, on March 12, 2008.
A pair of sandhill cranes pass in front of the moon shortly after sunrise at the Iain Nicolson Audubon Center at Rowe Sanctuary near Gibbon, Nebraska, on March 13, 2012. Sandhill cranes, which mate for life, can live between 20 and 40 years.
A windmill is dwarfed by storm clouds near Crawford, Nebraska, on May 3, 2017.
An early November storm system rolls through the Great Plains, but Omaha only receives rain, which collected on freshly-fallen leaves on Nov. 11, 2015.
Cattle head up to a well to get a drink at the end of the day near Sparks, Nebraska, on Aug. 21, 2015. Smoke from the wildfires in the western states created a haze.
The moon rises above the corn as farmers harvest the last of their fields in eastern Nebraska and western Iowa on Nov. 5, 2014.
Two riders help round up part of the 750 head of cattle branded at the Lute Family Ranch, located south of Hyannis, Nebraska, on May 12, 2005. Mick Knott, who runs the ranch, owns about half the cattle, and the Lute Foundation owns the rest. The work started about dawn and finished about noon.
The rising sun illuminates a tree and a windmill in a snow-covered field located on U.S. Highway 20 between Rushville and Chadron, Nebraska, on March 1, 2017.
The College Home Run Derby was held at TD Ameritrade Park and was highlighted by The World-Herald's annual Independence Day fireworks display on July 2, 2015.
Fog rises from the Missouri River and covers the Bob Kerrey Pedestrian Bridge on Jan. 5, 2010.
The weekend's perfect weather colored the clouds at sunset south of Wymore, Nebraska, on Oct. 23, 2004.
Deer chill out at Chalco Hills Recreation Area on Feb. 22, 2018.
A leaf is covered in a dusting of snow near 138th and Hickory Streets on Dec. 18, 2014, in Millard.
A runner emerges from the edge of the rising sun on Sept. 11, 2015, at Zorinsky Lake Park and Recreation Area in Omaha.
Nearly 45 minutes after sunset, an orange and blue glow is seen setting behind the Omaha skyline flanked between trees in Council Bluffs on Jan. 11, 2018.
Rain drops collect on a flower following early showers on May 10, 2017, in Millard.
The promise of rain is fleeting for the seven windmills on the Watson Ranch north of Scottsbluff, Nebraska, on U.S. 71 on May 16, 2004.
A crescent moon sets behind the UNO bell tower on Nov. 6, 2013.
Ralph Remmert is depicted in the mural "Fertile Ground" near 13th and Mike Fahey Streets in north downtown Omaha on June 19, 2017.
Ralph Kohler, 94, keeps his eyes to the sky for ducks and geese as the sun rises over his hunting pond east of Tekamah, Nebraska, on Nov. 30, 2011. Kohler has been a professional guide for most of his life, and he is preparing for the spring season.
The sun rises over St. Paul Lutheran Church, located three miles north of Republican City, Nebraska, in March of 2004.
Geese are silhouetted in the color and clouds as the sun sets at Zorinsky Lake on Feb. 21, 2016.
The sun rises on Chimney Rock on Wednesday, Feb. 19, 2014, near McGrew, Nebraska.
Cranes walk through the shallow water of the Platte River shortly before sunset near The Crane Trust, which is close to Wood River, Nebraska, on March 13, 2012. The river provides cranes with a safe place from predators for rest at night.
A bespangled vest awaits a rider during Nebraska's Big Rodeo on July 25, 2013, in Burwell, Nebraska.
Horses stand in the snow on Feb. 22, 2018.
Residents of the Nebraska Panhandle enjoyed unseasonably mild temperatures and cloud cover on Aug. 12, 2004.
Members of the Professional Rodeo Cowboys Association hold their hats as 2013 Miss Burwell Rodeo Olivia Hunsperger passes by during the opening ceremonies on July 27, 2013, in Burwell, Nebraska. "This may be a small town, but it's got a big rodeo, and it's got a really big heart," Hunsperger said.
A break in the clouds highlights downtown Omaha as seen from Lewis Central High School in Council Bluffs, as severe storms passed through the Omaha Metro area on June 5, 2014.
John Wanief waits for the bus in a shelter at 120th Street and West Center Road as cold rain pours down in Millard on Nov. 11, 2015.
Flocks of waterfowl fill the sky as the sun rises over Ponca, Nebraska, on March 3, 2018.
A red tail hawk perches on a light stanchion backed by the moon and overlooking the property near the Indian Creek development in Omaha on Feb. 27, 2018.
A woman walks with two dogs in Memorial Park near Dodge Street as many sledders go down the hill in Omaha, Nebraska, on Feb. 2, 2016. MATT MILLER/THE WORLD-HERALD
The sun sets over Sidney, Nebraska, on June 2, 2015.
The rising sun shines on a snow-covered hill located north of Chadron, Nebraska, on March 1, 2017.
Storm clouds are illuminated by the setting sun as people exit a football camp in Lincoln on Friday, June 16, 2017.
Sharon Vencil walks her dogs, Blackie and Whitie, along the Field Club Trail on March 6, 2018, in Omaha.
The morning sun burns off a layer of fog just north of the Chimney Rock.