I have never see a worm eating the fruit of a Meyer lemon, nor any lemon nor citrus of any kind. I suggest you phone your nearest University Extension Office or the US Department of Agriculture immediately, without delay and report this pest to them. Also clip off the fruit and put the fruit along with the pest into a large jar or ziplock bag, close tightly with adequate air inside. Make sure no one tampers with that bag or jar. You need to show the evidence to someone official, either a Farm Advisor or an Agricultural expert. Please take this advice seriously and act on it quickly before the pest dies.