Blackflies are small, soft insects. They use their suckers to drink sugar-rich liquid from plant leaves. Blackflies reproduce quickly, and they can form populations of thousands of individuals. 

Beetles are hard-shelled insects. They have six legs and four wings. Beetles have two flying wings that are protected by two thick wings also known as wing cases.

The ladybug is the most widely known type of beetle. It has red wing cases covered with black dots. 

 

Both ladybug larvae and adult ladybugs like to eat blackflies. When blackflies gather on plant stems to suck the sugar from plants, ladybugs arrive at the scene to eat them. When this happens, you can sometimes see ants protecting the blackflies from ladybugs. 

Why does this happen? The ants protect the blackflies from predators because they "milk" the sweet liquid secreted by blackflies themselves. The relationship between blackflies and ants is therefore mutually beneficial: the ants receive food from the blackflies, whereas the blackflies are protected by the ants.