Suet is usually a good bait for starlings, but I think winter time is the main time to catch starlings with bait.
I switched to millet as the feed in my trap last week and have caught several sparrows since then. Up to ~100 sparrows and starlings killed since I moved in last year but they still keep coming! One or two male HOSP’s insist on perching on my purple martin house and I have yet to take them out, will only be a matter of time though!