Thanks for your question.

In one of your pictures, I note that you have a plastic trunk protector on the tree. Be aware that after a few years, this can be removed. See the following for some additional information:

https://extension.umn.edu/fruit/growing-pears - protecting-trees-through-the-winter-668313

From your pictures alone, I cannot determine a single reason why the leaves are curling. Here are some possibilities:

1). There is something called a Pear Curling Midge (Dasyneura mali). However I cannot find any evidence that reports its finding in Minnesota. So although very unlikely but just for your information, see:

https://treefruit.wsu.edu/crop-protection/opm/pear-leafcurling-midge/ - :~:text=The pear leafcurling midge overwinters,harbor up to 30 larvae.

2). A disease called Fire Blight is rather common among many different types of fruit trees, including pears. It is caused by a bacteria known as Erwinia amylovora. One of its characteristic symptoms is the presence of openings (i.e., cankers) on stems with a watery ooze coming from them. See:

https://ohioline.osu.edu/factsheet/plpath-fru-22-0

https://treefruit.wsu.edu/crop-protection/disease-management/fire-blight/

https://extension.umn.edu/fruit/growing-pears - fireblight-676560

3). Finally as you mentioned in your question, there are certain mites (such as Phytoptus pyri) that can produce symptoms similar to what you are seeing in your trees. Based upon the very limited information that I could find, this is not common in Minnesota. See:

https://treefruit.wsu.edu/crop-protection/opm/blister-mites/

https://bugguide.net/node/view/1547794

See the following for information on these and other possibilities:

https://www.gardeningknowhow.com/edible/fruits/pear/leaf-curl-on-pear-trees.htm

https://portal.ct.gov/caes/fact-sheets/plant-pathology/disease-control-for-home-pear-orchards - :~:text=Several fungicides are effective for,leaf spot, and sooty blotch.

Here’s the bottom line. From just your pictures, I am unable to provide a single and certain explanation for what is going on with your two pear trees.

As a first step, I would suggest that you contact a licensed, professional arborist to make an onsite inspection. Often there is no charge for this. See:

https://extension.umn.edu/planting-and-growing-guides/how-hire-tree-care-professional

Then secondly as a check on what this arborist might tell you, submit pear samples to one of the following plant disease diagnosis laboratories. Contact them first before sending in any samples as to what should be submitted:

https://pdc.umn.edu/

https://pddc.wisc.edu/

Good luck. Please feel free to get back to us with any additional questions. Thanks for consulting us.