Picnic pests are small insects that can ruin a summer outing. Ants, with four letters, are one of the most common picnic pests. They are attracted to food and can quickly swarm a picnic area. Skeeters, with eight letters, are another common picnic pest. These flying insects can be annoying and can carry diseases. Gnats, with five letters, are also a nuisance at picnics. They are small flying insects that can be difficult to swat away.