Bark beetle

The bark beetles, which grow to be about 1/8" long. (Courtesy of U.S. Forest Service / February 13, 2014)

As California continues to experience extreme drought, the far-reaching effects of abnormal weather patterns are being observed locally in tree populations and the unwelcome guests they may be housing.

The city is warning La Cañada residents to be on the lookout for signs of bark beetle infestation in trees on their property. The small, boring insects pose a special threat to pines and other conifers in dry weather conditions.

"Pines need moisture to produce the defensive sticky substance required to repel the bark beetle when attacked," reads a Jan. 29 warning posted on the city's website. "With no or little rain this season (we) would suggest residents provide supplemental watering now, into and past this coming summer season on all species of trees, especially pines."

Gonzalo Venegas, La Cañada's facilities and maintenance superintendent, said the warning was issued after larvae were found in wood from trees removed by city workers.

Bark beetles, which tend to kill the tree from the top down, propagate in areas where trees are in high concentrations. To mitigate the infestation, the city is currently examining trees during routine trimming maintenance and has begun supplemental watering. According to Venegas, drought poses several risks to trees.

"Drought-stressed trees slow their growth. If trees are deciduous in nature, they turn their fall color and lose leaves earlier than normal. Seed production may be heavier as well as the tree spends more energy on reproduction," he said.

Venegas suggests residents examine trees for small holes or weeping sap in trunks and larger limbs. Other visible signs of bark beetles may include observable excrement and sawdust on the bark or at the base of the tree.

Although bark beetles have been found inside city limits, Descanso Gardens has not yet observed signs of infestation. Rachel Young, director of horticulture and garden operations at Descanso attributes this to the fact that many of the trees are deciduous.

"We don't have very many pine trees," Young said. "We're lucky in that we have a lot of natural land nearby, and it kind of gives us a buffer zone."

Meanwhile, to prevent drought stress, staff members are deep-watering ornamental trees on the garden grounds that aren't equipped to handle drought like native trees. To prevent the further spread of insect infestation, Young suggests campers refrain from moving firewood from place to place.

"That's one of the biggest ways infestations spread," she said. "If you're going camping in Big Bear, just make sure you buy your firewood there. Don't bring it with you."

More information on bark beetles and measures residents can take to stop the spread of infestation is available on the city's website, www.lcf.ca.gov.

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SARA CARDINE is a freelance writer. She can be reached at s_cardine09@yahoo.com.

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