Parasites live in, or on, other organisms. All parasites want to find and successfully infect a host so that they can live and reproduce. It’s hard and risky for an individual parasite to infect a host – a group attack is a safer option. Insect-infecting nematodes use this strategy by following environmental signals, such as plant volatiles (scents). We wanted to see if past experience with some volatiles changes the infection behavior of nematodes. We treated the host environment with different concentrations of two volatiles known to have an influence on nematodes and observed the infection success. Our experiments showed us that the nematodes’ past experience alters their infection behavior.