Adult carpet beetles, which feed on pollen and similar, are tiny (about 1/16 to 1/8 inch) round beetles that are black to mottled brown/black. The brown larvae, also about that size and bristly, like to chew fabric. If the bodies that you see are silver and fish-shape, those sound more like silverfish, or possibly pillbugs or sowbugs (are they segmented?). Pillbugs/sowbugs feed on rotting wood. Silverfish are attracted to moisture and carbohydrates, and may sometimes feed on fiber, such as carpet, if their preferred food is not available. The fact that these insects are found under the windows might suggest some moisture around that area occurred at some point. Is there any evidence of past leaks from the window(s)? It may also be possible that the patches were indeed caused by carpet beetle larvae but also that moisture drew in the silverfish. You might check for more evidence of both pests. Various moth larvae (such as those from the common and case-making clothes moths) can also chew carpet. Carpet beetles can be one of the more destructive. Check for discarded shells, frass, cocoons, and other clues to help determine what insect might be the culprit. Hope this helps!
Adult carpet beetles, which feed on pollen and similar, are tiny (about 1/16 to 1/8 inch) round beetles that are black to mottled brown/black. The brown larvae, also about that size and bristly, like to chew fabric. If the bodies that you see are silver and fish-shape, those sound more like silverfish, or possibly pillbugs or sowbugs (are they segmented?). Pillbugs/sowbugs feed on rotting wood. Silverfish are attracted to moisture and carbohydrates, and may sometimes feed on fiber, such as carpet, if their preferred food is not available. The fact that these insects are found under the windows might suggest some moisture around that area occurred at some point. Is there any evidence of past leaks from the window(s)? It may also be possible that the patches were indeed caused by carpet beetle larvae but also that moisture drew in the silverfish. You might check for more evidence of both pests. Various moth larvae (such as those from the common and case-making clothes moths) can also chew carpet. Carpet beetles can be one of the more destructive. Check for discarded shells, frass, cocoons, and other clues to help determine what insect might be the culprit. Hope this helps!