Using wildcards in names in Windows hosts file
There is not. The hosts file isn't very clever, you have to list every subdomain individually (including www and no-www)
An answer to a very similar StackOverflow question worked well for me.
Wildcard Support on XP at hostsfile. Enjoy.
Basically, this program Acrylic works as a DNS proxy for your local machine. Just point your Local Area Connection to 127.0.0.1, then edit the AcrylicHosts.txt in a very similar manner to the regular hosts file -- only with wildcards!
Dnsmasq is what you need but it doesn't work quite well on Windows. So I wrote an alternative on Windows called DNSAgent.
You can use regular expression in rules. There is also some advanced features like customizing cache TTL, non-standard-port DNS server, compression pointer mutation, etc. Open sourced under MIT license.