Typically you can tell by their colors. Girls will get their mature female colors (green base with blue and yellow spots) around month 6-7ish. At this point they can start laying infertile eggs, so it's prudent to have a laying bin ready for them starting at about month 5-6, because recognizing the signs of needing to lay (especially the first time) can be tricky.
Is it common for females NOT to lay eggs after maturing? Mines about a year, I've got a laying bin available with varying moistures, but she's never laid! Her belly never even got swollen... Been puzzling over this for a while!
There are things you can do to keep them from laying, perhaps you're doing it as a happy accident. By keeping her temps a little cooler (close to 80F) and not feeding her as much daily/every other day she may not produce eggs at all. One member had a female veiled live to 8 years of age, not having laid eggs once in her care if I remember correctly.
Since Jackson's are live bearing you don't really have the same concerns. They may still develop a clutch of duds but this is fairly unusual, so typically females won't do anything without a male in the mix.
She's relatively cool, ranging from 80-95ish. I feed her about 20 crickets every 2 days. Lately she hasn't been eating them all though so ill probably cut back to 15 every other day. Thanks for the info!
You want the MAX cage temp to be about 80-83F and the ambient temps to be lower, so in the 70's somewhere. And 15 crickets in one day may a lot, but I guess it depends on the size of cricket you're using.
Very helpful link! The crickets are generally small to medium... Every once in a while ill actually fin some larger ones, so ill be sure to keep the number down at those times.. Thinking about getting some hornworm eggs soon to start a project