There are four tree-eating bugs that Nebraska Extension entomologist Jonathan Larson is watching out for this year. They include native ash borers, bagworms, and the European elm flea weevil.
But Larson believes Japanese beetles, which are relatively new to Nebraska, pose the biggest threat.
“It’s this green and orange beetle, that’s about the size of a black bean, and they just show up in these huge masses and they’re like a swarm of locust,” Larson tells Nebraska Radio Network. “They can come through and consume your roses, many of your tree species, fruits and plants like that. Then, they lay their eggs in your lawn and the grubs can destroy pieces of your turf.”
Larson says the weevil on the list is a tiny insect that can cause a lot of damage, but does not usually kill a tree.
“As a little grub, it will create these little mines in the leave. It’s so small it can live between the layers of the leaf,” he says. “Then they emerge as an adult weevil and they will chew through the leaf and create what we call shot hole damage. It looks like somebody has taken a shotgun.”
Larson says elm trees can have a host of problems and the weevil is just another one for the list.
While Nebraska is waiting for the Emerald Ash Borer to wreak havoc, other varieties of the bug already pose problems. There are three of them that Larson is looking out for, but he says they are not as destructive as their emerald cousin.
“They normally are going to find trees that are already stressed. So, you can maybe put one and one together and end up with three that they cause some of this damage.”
The bagworms are caterpillars usually found in juniper trees.
“They collect those needles and berries, and they sew it together with silk and make this bag that they live in,” Larson says. “From inside this bag, they’ll pop out and they’ll start chewing on the leaves of the tree. They can create bronzing and thinning, and they can just be really destructive to a lot of our favorite evergreen plants.”
Larson says you start to see the bags in the tree in May and June, but for tree owners, vigilance is needed all summer long.
“If these trees are really a valuable piece of your property, they shade your home, or they have limbs that hang over your house, you want that tree to stay healthy, you need to take a close look at it every so often,” Larson says.
He recommends a close inspection at least once a month in the summer. Larson says the sooner you spot a problem, the more likely it is you can save the tree.