Iowa snowmobiling enthusiasts need to check the registration stickers on the sides of their machines — or they may soon be riding them illegally. Steve Schutte, a law enforcement officer with the Iowa Department of Natural Resources, says the stickers expire December 31st.Schutte works out of the D-N-R’s Clear Lake office. He says younger Iowa teenagers who want to drive snowmobiles are under strict rules. They have to be carrying a snowmobile safety certificate with them at all times they’re driving on public land — even if it’s just for a minute.Schutte says there must be a flag on your snowmobile. He says it’s not just a safety precaution, it’s the law. Schutte says snowmobiles must be used off the road. He says most snowmobiling accidents in Iowa are alcohol-related, especially at night.