The "ladybugs" in the video below aren't native to the US. The are known as the Asian Ladybeetle, and while more a nuisance than anything else, can make it unpleasant to be outside when they're swarming. This usually happens in mid Autumn, on warmish days. The bugs also have a sharp little bite, and unhelpfully, sound just like a wasp (which also come out on warm autumn days) when they buzz by your head.
This species became established in North America as the result of introductions into the United States in an attempt to control the spread of aphids. In the last three decades, this insect has spread throughout the US and Canada, and has been a prominent factor in controlling aphid populations. The first introductions into the US took place as far back as 1916. The species repeatedly failed to establish in the wild after successfully controlling aphid populations, but an established population of beetles was observed in the wild near New Orleans, Louisiana, in about 1988. In the following years, it quickly spread to other states, being occasionally observed in the Midwest within five to seven years and becoming common in the region by about 2000. The species was also established in the Northwest by 1991, and the Northeast by 1994, aided by additional introductions from the native range, rather than just reaching there from the Southeast. Reportedly, it has heavily fed on soybean aphids (which recently appeared in the US after coming from China), supposedly saving farmers vast sums of money in 2001.
In the above video, I think the damage was caused by carpenter ants. The two old windows on the second floor leaked (and will ultimately be replaced), letting water into the house framing.
See more here - "How to Identify Carpenter Ant Damage"
It’s consistent with the other damage I found in the house. Any place there was water infiltration, to where the wood would be soaked repeatedly, there were tunnels. As far as leaving the damaged wood in place -- long as you stop the water from coming in and replace the rotted wood everything should be ok. I didn't see any live ants or their eggs.