I suspect the mites on the red mason bee cocoons are Chaetodactylus osmiae but the mites on the leaf cutter cocoons are different...I'm not a mite expert.....someone may find this interesting though!
see them here...... http://bit.ly/18nQ7Av
Cheers George Pilkington
..article now updated with probable identity of other mite..ID'd by professional...... George Pilkington