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Big bugs stalk city

Cinara aphid and clover mite spotted in town

By: Kevin Ma

  |  Posted: Saturday, Jun 11, 2011 06:00 am

Cinara aphids, pictured here, have been found in unusual numbers this month on spruce trees in St. Albert. The big, but mostly harmless bugs suck sap from trees, stunting their growth.
Cinara aphids, pictured here, have been found in unusual numbers this month on spruce trees in St. Albert. The big, but mostly harmless bugs suck sap from trees, stunting their growth.

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Crimson swarms and big black monsters are swarming some local trees and lawns. But don’t worry, says the city — these bugs are mostly harmless.

City staffers started getting calls about cinara aphids on spruce a few weeks ago, says city arborist Kevin Veenstra. Initially spotted by students around Elmer S. Gish and Muriel Martin schools, the bugs have since been identified in Woodlands, Deer Ridge and Akinsdale.

Cinara aphids are black or brown insects that feed on pine or spruce trees, Veenstra notes. They’re also huge, averaging about four millimetres in length.

“Their proboscis is longer than their body!”

These bugs are native to St. Albert, Veenstra says, but have turned up in much greater numbers this year. “The stems are black [with bugs],” he says. Most infestations are limited to three or four trees in a yard. “It’s a lot worse than we’ve seen in the past, but it’s localized.” He blamed the infestation on dry weather.

It has been pretty darn dry lately, agrees Ralph Wright, soil moisture specialist with Alberta Agriculture. About 35 millimetres of rain have fallen on the St. Albert region since April 1, he notes — far below the usual 80. Provincial moisture maps suggest this to be a roughly one-in-12-year low. We’ve yet to hit the rainy season, he adds, referring to the end of June/start of July, so it’s too soon to tell how this will affect farmers.

Big, but harmless

Cinara aphids are some of the largest aphids in the world, according to Jill Sidebottom of the Mountain Horticultural Crops Research & Extension Centre in North Carolina, and are sometimes mistaken for ticks. They often show up on Christmas trees. Aphids lay eggs and give birth to live young, allowing them to build up their numbers rapidly.

They’re kind of the monsters of the aphid world due to their size, says Jim Hole of Hole’s Greenhouses & Gardens, but are basically harmless. “It’s a minor pest,” he says — they’ll stunt a tree’s growth and cause a sooty black fungus on branches, but that’s about it.

Ants are a telltale sign of these bugs, Veenstra says, as they feed on honeydew. “They nurse the aphid colonies like dairy cattle,” he says, and you’ll often see long lines of ants marching to and from them.

You can blast the bugs with insecticidal soap if they annoy you, Hole says, but that’s probably not necessary. “You don’t have to eradicate every last aphid.” Other bugs, such as ladybugs, will eat them for you as well.

The city has no plans to spray these bugs, Veenstra says. He suggests residents water their trees to help them fight off the bugs.

The red scare

Staffers have also received one report of a red clover mite infestation in the Mission region.

These pinhead-sized grass-suckers are notorious for invading homes en masse, where they don’t do much except crawl around and freak out people. “When you squish them,” Veenstra says, “it looks like blood.” (It’s not blood, say entomologists, but body pigments.)

Red clover mites are one of the first pests to show up in the spring, Veenstra says, and are known for their super-long front legs. They tend to show up in new lawns or gardens where they suck sap from grass.

These mites won’t eat your houseplants, Hole says, but they will leave an icky red stain if you squish them. Use a vacuum to catch them instead. You can spray them with insecticide, but that’s probably over-kill.

Clover mites tend to gather in huge masses around cracks in your house, Hole says. To keep them out, simply seal those cracks.

Any questions on either of these bugs should go to public works at 780-459-1557.


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