Hundreds of thousands of ‘problem’ caterpillars disappear from the North Okanagan

They appeared from nowhere in the hundreds of thousands a few years ago, but as quickly as they came they now have all but disappeared.

The Western yellowstriped armyworm, which is a type of caterpillar, appeared in the North Okanagan in 2018 and posed a serious concern to many of the region's farmers.

They'd never been seen before in the area, which alarmed farmers and gardeners and had the Ministry of Agriculture seriously worried.

READ MORE: Rare caterpillar outbreak in North Okanagan has government officials investigating

The insects showed up again in 2019 in high numbers and the Ministry kept monitoring the caterpillars.

One farmer talked of "black roads" from all the vehicles running over them.

However, after two years of the armyworms infesting parts of the North Okanagan, the insects have now all but disappeared.

There was no damage to crops and very few have been seen in the last two years.

"While we caught a few moths (in 2021), numbers remained low and there have been no further outbreaks of armyworms in the North Okanagan since 2019," Ministry of Agriculture entomologist Susanna Acheampong told iNFOnews.ca in an email.

The news is a welcome relief for farmers because the caterpillars feed on alfalfa, corn and a variety of other crops, which was causing concern for farmers.

READ MORE: 'Problem' caterpillars return to North Okanagan

Acheampong had previously said in 2019 it was very difficult to control the caterpillars.

For the last few years, the Ministry has been monitoring the armyworms and using pheromone traps to capture the moths. With such a small number of moths caught last year, the Ministry is now confident the caterpillars are not a problem and has scrapped the monitoring program for 2022.

But where did the caterpillars come from in the first place?

"Possibly northern California," Acheampong said. "Preliminary results from moth wing analysis suggest that the outbreak in the North Okanagan in 2019 was from large numbers of moths coming in on wind currents."

The government scientist said which years a migratory insect may appear is difficult or impossible to forecast, and scientists don’t always know what factors influence the migration.

So, those worried about another onslaught of caterpillars need not worry, at least not this year.

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