Drop one in there, see if he / she likes it. I assume bugs have varying tastes and we know Betta's have taste buds with some of ours being picky eaters.
My male attacks spiders....absolutely can't get enough of em. Caught some weird looking fly and dropped em in there over the weekend, did not like it at all. Took a peck and left it alone so I scooped the fly up in a spoon and dropped it in the sorority tank where he soon became a meal