Thistle caterpillar has been noted in some soybean and sunflower fields. Manitoba Agriculture Entomologist, John Gavloski, says he's been fielding calls from across the province of the highly-visible insects.

"They tie leaves together with webbing, so you'll get these nests made of webbing and the caterpillars like to live inside those nests and they'll be feeding inside them, they produce a lot of feces so you get these black droppings in the nest and it's very visible up on the plant."

Gavloski adds the caterpillars don't usually cause a lot of damage to crops and doesn't expect the population to reach economic impact levels this year. The insects migrate into Manitoba from the southwest U.S. states and Gavloski says this year there was quite a large migration that took place.

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Meantime, some levels of Diamondback Moth larvae approaching threshold have been noted in some canola fields in the southwest. Gavloski says trap counts are quite low, however there are a few fields reporting about 10 or 15 larvae per foot square a plant.

"If they do some feeding on some buds and flowers the plants can compensate really well, so with canola you can remove quite a bit of buds and flowers and the plant produces more. So, if you've got good soil moisture and the plants are able to compensate, that bud and flowering feeding is usually a very marginal consequence."

He adds however, it's good to know what the levels are like for Diamondback Moths when canola goes into the podding stage. "That's where they can do damage that the plant can't compensate as well for."

Gavloski points out that a heavy, pounding rain storm can serve as a natural mortality factor in dealing with Diamondback Moth larvae.

As for Bertha Armyworm populations at this time, Gavloski says trap counts remain quite low across the province.

"So far our highest trap is two hundred and twenty-five in the northwest, everything in the eastern part of the province is quite low - well below a hundred."

He notes trapping will continue for another two or three weeks, but says the insects aren't looking threatening to Manitoba crops.