In vertebrates, it is well documented that the parental consumption of high-fat diet increases the risk of Attention-Deficit Hyperactivity Disorder (ADHD) in offspring. While insects have long been used as popular study organisms in various biological research, few studies have explored how the nutritional quality of parental diet affects offspring behavioral phenotypes associated with ADHD in insects. Here we used the bean bug, Riptortus pedestris (Hemiptera: Alydidae), as a study organism to test the effect of parental high-fat diet on offspring hyperactivity, impulsivity, and diffuse attention, which are widely held as the three core symptoms of ADHD in vertebrates. Peanut was used as the high-fat diet while soybean was the control. Parental high-fat diet consumption induced hyperactivity in R. pedestris offspring. Compared to the controls, the hyperactive offspring of parents fed on high-fat diet were behaviorally more impulsive and less attentive, as they were found to be highly attracted to visual stimuli but losing attention easily. Collectively, these results provide the experimental evidence that the parental consumption of high-fat diet results in increased hyperactivity, impulsivity, and diffuse attention in an insect. This study implies that the well-known association between parental high-fat diet and offspring ADHD is conserved across the tree of life and opens up the new horizons that insects can arise as novel and feasible models for studying the mechanism and evolution of this common neurodevelopmental disorder in humans.