Depending on food sources and climate larvae may take over a year to develop into adults. Once inside carpet beetles expand their diet to include hair fur silk wool clothes and other fibrous material. How To Tell The Difference Between Bed Bugs And Carpet Beetles Both carpet beetles and bed bugs can cause welt like rashes. Bed bug carpet beetle . Carpet beetles look very very different from bed bugs when they are larger. Bed bugs actually create red itchy welts on the skin from biting you while the carpet beetle doesn t bite at all but causes a similar red itchy welt due to an allergic reaction from the prickly little hairs on the carpet beetle larvae pictured center. They look like tiny furry caterpillars whereas the bed bug larvae look a lot like the larger versions but just very small. Bed bug larvae look like little worms while carpet beetle larvae look like fuzzy bugs with little spines all over them. However rashes from bed bugs are from bites while rashes from carpe...