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Northern Gardening: Possible new garden pest located

Earlier this year, I discovered a cluster of small brown caterpillars under two adjacent leaves on my Saskatoon bush. I destroyed them and examined the shrub carefully, but did not find any more.
caterpillar

Earlier this year, I discovered a cluster of small brown caterpillars under two adjacent leaves on my Saskatoon bush. I destroyed them and examined the shrub carefully, but did not find any more. Hoping the threat was dealt with early enough, I soon forgot about it. There was no damage and no infestation.

About a month later, my Ohio buckeye tree was showing a few leaves skeletonized at the top of the tallest branch. Being very busy at the time, I did not examine it until a few days later, when I noticed the damage was progressing down the branch. On examination, I discovered a cluster of full sized caterpillars on the underside of the leaves just below the eaten ones. I hand-picked them and destroyed them, then researched what they might be.

Identification of this caterpillar with a red head and a red spot on its back was not difficult. The redhumped caterpillar, Schizura concinnea, occurs from southern Canada throughout the United States, with the heaviest populations in California and the eastern states from Florida, up into southern Ontario, Quebec and the Maritimes. Occurrences are heaviest in the south with decreasing density moving north. Interestingly, reported sightings on the prairies are limited to Winnipeg, an unnamed site north of North Battleford and our report confirmed by our photograph submitted to inaturalist.org. It appears that this pest is expanding its range northward.

The adult stage of the redhumped caterpillar is an inconspicuous greyish-brown moth. The adults emerge from cocoons in the ground in June and July. The female moth lays eggs in clusters of 40 to 100 on the underside of leaves from a wide variety of trees. The eggs hatch into caterpillars that feed first on the underside of the leaves, but as they grow they consume entire leaves except for the tough mid ribs. The caterpillars from one egg mass stay together on the same limb and feed in groups. There is no tent or nest. They mature in August, after attaining a length of one to one and one-half inches. At this point, they move to the ground and spin a cocoon under litter, where they overwinter. They pupate in spring and the adult moth emerges in early summer, completing the cycle.

I am curious if anyone else in the area has found this caterpillar. I will be monitoring its occurrence in my yard, but would be interested to know how prevalent they may be around here. It would also be helpful to report sightings to inaturalist.org by submitting a photograph of the caterpillars.

 

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