Cold weather’s effect on bug populations

It’s too early to tell if anything good could come of the Grand Valley’s bitterly cold winter. You might think that more than 20 days of below-zero temperatures might guarantee fewer problems with pests in the spring, but you shouldn’t count your squash bugs before they hatch.

“I wouldn’t hold my breath,” said Colorado State University Extension entomologist Bob Hammon, when asked if the brutally cold temperatures might kill off future insect populations.

There are more factors involved in bug populations than cold. Some insects might be thwarted by our icy winter, but they could migrate here later from warmer climates. For instance, insects such as the Russian wheat aphid or corn earworm could just migrate over to our gardens from sunny Arizona, Texas or Mexico after the winter passes. Other insects, such as grasshoppers, overwinter here in a form less susceptible to cold.

“Grasshoppers are in the egg stage, down in the soil and they’re resistant to a lot of cold,” Hammon said. “What they can’t handle is a lot of moisture,” which could come in the springtime, but it’s too early to tell.

“I’m not sure what the impact of this cold is on bugs, but I’m playing it safe and telling people to prepare to deal with everything,” Hammon said.

Although it’s not certain if the freezing temperatures will affect insects, it surely will cause damage in some plants, shrubs and trees.

Hammon is expecting his fig tree to die back to the ground, even though it’s planted on the sunny southwest side of his home, and is slightly protected by its proximity to the house.

“There’s a lot of stuff that’s going to die back to the ground,” he said. Tender plants used to milder winters may be a total loss or experience significant damage. “That’s the chance you take when you plant something that’s not adapted to the area and it gets 15 below.”

Although many commercial orchards in the valley have started pruning operations, Hammon advises home orchardists to wait. Commercial orchards begin pruning much earlier simply because of the amount of pruning they must accomplish before springtime. However, if you have only a few trees, you have the luxury of waiting to prune just before bud break, which is preferable.

“Especially on the more tender trees, like peaches and cherries, I would wait,” he said.

Also, the lack of moisture except for the snow that has stayed on the ground since December may cause problems for trees, especially if they are accustomed to more frequent watering or they aren’t fully established.

Normally, dragging out the hose to water these trees in the wintertime is recommended. However, the temperatures are simply too cold for this to be a good idea right now, because the water would just freeze and the tree wouldn’t benefit.

If there’s one positive thing about the frigid conditions so far in the Grand Valley, it’s that local gardeners will discover the truly hardy plants in their landscapes, depending on what survives.

“If it makes it through this winter, it will make it through most,” Hammon said.

ON ANOTHER NOTE: High Country Gardens has updated its status on its website. According to David Salman, the company’s founder and chief horticulturist, the business is keeping its mail-order business in operation, though its stores have closed.

I haven’t received a spring 2013 catalog yet, but if you join their email list at, I’m sure you will know the latest.

Erin McIntyre is a writer, master gardener and owner of the gourmet pickle company, Yum Pickles. Email her at .(JavaScript must be enabled to view this email address).

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