I was out of town for a couple days. A heat lamp on top of the cage activates them. Warm velvet ants will spend part of the day zipping around the cage. Problem is, a single velvet ant doesn't need much space and a lamp on top of a cage usually means you're running a ten gallon setup. It's for this reason I keep my velvet ants and my blue death feigning beetles in a communal cage. It helps to justify the practicality and expense of keeping a 60 Watt bulb running for 6-8 hours most days. Also, multiple bugs means they're disturbing each other more often and like bumper cars they're getting each other going. Makes for a more interesting display.
So, I feed them watered down maple syrup or watered down honey. I also toss in some bits of various fruits and the velvet ants will be seen sipping the juices on these. These are the cited velvet ant "staples" in captivity. I've also had success keeping them on the red hummingbird liquid if you don't want to mix. A heat lamp can dry out the little caps/lids of sugarwater mixture in a day or so, to the point where your pet bug can almost feel like a chore. Having some of that hummingbird liquid onhand means a quicker refill. Actually, because the lid usually dries out before the sugarwater is consumed, there is often some sugary residue or thickened syrup. I just use my misting bottle on a spray setting to fill the cap back up and I'm usually good for another day or two.
The bulb is in a cone shaped hood on top of a screened cage, more towards one end. I provide some opportunities for cover with rocks and wood, etc. They choose what temperature range they want to be in for the most part.
Velvet ants are pretty cute in the first place, but an individual will often utilize the same retreat each evening--like tucking itself into bed for the night in the same spot in a cage full of options.
All my care suggestions are based on ideals. Bugs are very forgiving pets and I've got a lot of them to watch over.
That D. sackenii is the only one I've seen of the species. It was collected in S. California. I do hope to get more in soon. The only one I have presently is a very unusual red and black one collected in Arizona. My daughter's pet "Ruby" died recently. She was a SE "cowkiller".