Functional response of the predator Chilocorus cacti (Linnaeus) (Coleoptera: Coccinellidae) on five densities of Dactylopius opuntiae (Cockerell) (Hemiptera: Dactylopiidae) female adults was assessed under laboratory conditions. The searching efficiency of C. cacti significantly decreased as prey density increased. The logistic regression for the predator had a negative and significant linear parameter indicating a type II functional response. Non-linear regression for Holling predator equation estimated a handling time of 1.79 ± 0.129 h and attack rate coefficient of 0.1003 ± 0.030. Most of this handling time was because the predator spent a lot of time removing the waxy coating that protects adult females of D. opuntiae. Chilocorus cacti consumes females of D. opuntiae in their reproductive stage; therefore, it could be an effective natural enemy to suppress or regulate low density populations of D. opuntiae, preventing them to reach high densities.