public class LeadUtils {
    @future public static void deleteJunkLeads(Id[] leadIds) {
        Id junkQueueId = [SELECT Id FROM Group WHERE DeveloperName = 'JunkLeadQueue' AND Type = 'Queue'].Id;
        delete [SELECT Id FROM Lead WHERE Id IN :leadIds AND OwnerId = :junkQueueId];
    }
}

trigger queueDeleteJunkLeads on Lead (after insert) {
    LeadUtils.deleteJunkLeads(Trigger.newMap.keySet());
}