Often times in the changes of the seasons, the inspection of mystery bugs turns up dermestid (flesh eating) beetles. The immediate response is one of disgust, but these little beetles are not as scary as they sound. They play an important roll in nature that answers the question of why ladybugs attract dermestid beetles.
The shortest answer to this question is that they do not. What is needed is a small clarification. Ladybugs are not typically structure infesting insects, and their populations are naturally kept in check. Their relative, the multi-colored Asian lady bird beetle has a different story. The difference between the two includes minor size differences, color variations, and differing pronotum markings. To keep it simple, the ones that swarm your home are the Asian beetles. The good guys we want to do well are the ladybugs.
The Real Source
When Asian beetles swarm the home, they are going to aggregate in tight clumps inside of cracks, crevices and wall voids to rely on conglomerate heat to survive the winter. Even if the home is well heated and the insulation is great, not all of the beetles will survive. The dead beetles combined with other bug parts left behind leave an open buffet for natures house cleaners: the dermestid beetles!
Why You Actually Want Dermestid Beetles
Dermestid beetles are wonderful for keeping dead bug carcasses from building up all over the place. They usually go unnoticed unless one really watches closely in nature or goes poking around in roadkill. When mass amounts of Asian beetles end up in one spot, it can be a huge motivator for the wandering dermestids to join forces and have a party in and around your home.
When seeing a large number of these, keep in mind they will disappear as the numbers of shed exoskeletons, wing parts, and dead bugs decrease. If they are of concern, treatment may be done to minimize them, but efforts are best spent in addressing the underlying source moving forward. Keep in mind these dermestids are not out to get you, but are simply keeping your house clean for free!