If electronic "aliens" think the Riverdale mayor and Town Council are going to stand idle while they continue to gobble residents' money, they're in for a surprise: Town officials want a piece of the action.

Beginning in July, the town will require operators of electronic games at retail stores to register their machines, estimate each one's gross intake and give the town 5 percent of that gross, according to Town Administrator Patrick Prangley.

Prangley, in explaining the council's action, said stores that have the machines tend to become hangouts for "undesirables" and require more police patrols. He said revenue from the new tax will be used for increased police protection. He added that the electronic games present an "increasingly attractive source of revenues" for the town.

Council members at Monday's session also passed an ethics ordinance for appointed and elected officials. Provisions included financial disclosure statements that must be filed with the state Ethics Board, provisions governing conflicts of interest and a ban on lobbying among officials, Prangley said.

The council also set up a five-member ethics commission to be appointed by the mayor and council later this spring.

The council members also approved pay raises for themselves and the mayor, according to Prangley. Starting in June 1983, the monthly salary for council members will rise from the current $75 to $125. The mayor, who now gets $150 per month, will be paid $200, Prangley said.

Some residents of the East Pines and Riverdale Woods neighborhoods walked away disappointed when the council turned down their request for annexation, Prangley said. The residents hoped to obtain city services, but the council decided most citizens opposed the annexation.