Observe the melons as they grow and mature, and wait for the green color between the netting to turn from a green to a tan or yellow color.
Muskmelons -- better known as cantaloupes -- are excellent melons to grow in the home garden. There are many varieties suitable for the home garden and “Harvest Queen” is a common choice, known for its orange flesh and resistance to fusarium wilt. Expect to harvest this variety approximately 90 days after planting, looking for signs that they are ready to pick about one week before this.
Look at the Harvest Queen melons where they attach to the vines. According to University of Illinois, they will be ready to pick when there is a crack in the melon near where it attaches to the vine.
Pull and twist the melons off the vines, or use a pair of pruning shears to clip them off. Harvest them in the morning after the dew has evaporated and the melons are dry.
Harvest the melons every other day, but in hot weather, harvest them every day so they don't over ripen in the field.