In this book chapter, you will learn how painted lady butterflies are used for CRISPR gene targeting experiments in an undergraduate biology course. We describe the advantages to using butterflies for undergraduate lab classroom, and the specific reasons that make them an undergraduate-accessible organism for gene targeting with CRISPR. Readers will learn about the benefits of the life cycle and husbandry of the butterflies and caterpillars. We discuss the overall CRISPR strategy and tools needed to deliver CRISPR components into butterfly eggs. We explain how CRISPR is used for loss-of-function gene studies, where CRISPR is used to disrupt the proper expression of genes involved in wing color and patterning. We show how a simple microinjection system and stereoscope is used to deliver CRISPR components into the eggs. Furthermore, we describe the molecular biology techniques used to determine nucleotide changes made by CRISPR and DNA repair mechanisms. We discuss how CRISPR of genes regulating wing color and patterning can show a visually drastic change that students find extremely fascinating, and thus enables students to make connections between genotype and phenotype.