Peninsula Spruce Threatened By Aphid

Apr 4, 2016

Spruce aphid
Credit Courtesy of the U.S. Forest Service

Spruce trees are under attack in the Kachemak Bay area. Tiny insects called spruce aphids are draining sap from the trees leaving tell-tale signs of damage. Spruce aphids are not usually found on the Kenai Peninsula and their sudden appearance is making residents worry for the health of their trees.

Spruce trees with uncharacteristically brown colored needles line the road leading up to Meghan Gervais’ home on the East End of Homer. Gervais says the trees are losing a fight with a parasite known as the spruce aphid.

“If you look here at the corner of McClay and East End Road, and all along the Homer Bench, you’ll see lots of brown trees and that’s from this spruce aphid,” said Gervais.

Spruce trees under attack by aphids.
Credit Photo by Quinton Chandler/KBBI

Gervais walks over beds of dead spruce needles to the boundary line between her property and her next door neighbor’s. Several spruces are grouped together on the property line partially blocking the view into the yard next door.

“You can see over here that tree is almost entirely defoliated and some of these are just partially green still. And if you look up close…,” said Gervais. 

Gervais grabs hold of an immature spruce’s branch and she points to a section of one of its needles that is still green.

“You can see on some of the needles just these little tiny aphids. You have to have really good eyesight,” said Gervais. “They’re really hard to see unless someone points them out but a tiny thing can sure do a lot of damage.”

That is a problem for Neil McArthur too. He’s Meghan Gervais’ neighbor.

“If all of my trees were to be gone, my wind break would be gone [and] my privacy would be gone,” said McArthur. 

But, McArthur isn’t too worried; after all, he says, the spruce survived the spruce bark beetle kill of the ‘90s.

“I think we’ll still have spruce trees despite all these things,” said McArthur.

Meghan Gervais, her daughter Margaret and Neil McArthur stand in front of several spruce trees.
Credit Photo by Quinton Chandler/KBBI

But, Gervais wanted more assurance so she asked Janice Chumley to come to Homer and take a look. Chumley is a research technician who handles integrated pest management for the Kenai Peninsula Cooperative Extension Service. She breaks down the situation.

“Well an aphid is a very small insect. They’re soft bodied and they tend to feed by sucking the sap out of things. They repopulate themselves through a great concept known as parthenogenesis which means that they mate once and then they’re all born pregnant females,” said Chumley. 

Chumley says aphid populations grow at a rapid pace and the sap in spruce needles is the bugs’ favorite fare.

“…whether it’s Sitka spruce, or White spruce, or Lutz spruce,” said Chumley. 

Chumley says spruce aphids are an invasive species from Europe. They’ve been found in Southeast Alaska for decades and they’ve also been seen in Kodiak and in Prince William Sound, but they hadn’t ventured into the Kenai Peninsula until last year. Halibut Cove, a community southeast of Homer across Kachemak Bay, noticed them first. 

“Residents of Halibut Cove had observed it and were very curious about it and then residents on the Homer Bench, and this really is related to the bench. It’s a very coastal insect feeder,” said Chumley.

On the Homer side, Chumley says the infestation extends from mile 7 on East End Road up to about 350 feet in elevation.

“Higher elevations will not find this at all but coastal trees are the ones that are highest at risk,” said Chumley. 

Chumley says the aphids are spreading in Homer because of the recent weather conditions.

“The last couple of springs have been really warm and dry, and trees like to have it a little cooler and moister. And in addition to that, what would help to lower the population of these aphids would be a really cool winter and for the last couple of winters that has not happened,” said Chumley. 

Still, Chumley says it’s unlikely the pests will kill large numbers of spruce.

“It’s going to make them a little funny looking though. Trees that are normally full and lush will become a little more sparsely needled,” said Chumley.

Spruce trees with less pronounced signs of aphid infestation
Credit Photo by Quinton Chandler/KBBI

Chumley says the property owners could spray pesticides to kill the aphids or they could just water the trees.

“Good ole strong stream of water can knock these aphids off. It’s not going to kill them but they’re not strong fliers so it will lower the population,” said Chumley.

Gervais and McArthur like the second option.

“I have kids and I don’t want them exposed to any additional chemicals,” said Gervais.

To learn more about spruce aphids you can contact Janice Chumley at the Kenai Peninsula Cooperative Extension Service or call the U.S. Forest Service.