Tracker jackers are genetically-altered wasps, conceived and created in the labs in the Capitol. They are genetically coded to attack anyone or anything that disturbs their nest. Once they make a person their target, they will follow him or her far away from their nest, unlike natural vespids. Tracker jackers were used as weapons during the war and planted around the districts of Panem. After the Dark Days, the Capitol destroyed some hives around themselves, but still kept the hives around the districts as a cruel way to show their power over the inhabitants.Tracker jackers look like normal wasps, except for their larger size and golden coloration.
The swelling caused by the stings commonly range from the size of a plum to the size of an orange, and reach their full size only a few minutes after the initial sting. If the barbed stinger is torn out, the entry hole oozes a foul-smelling green liquid. The stings themselves are extremely painful, and remain so for days unless treated.
Tracker jacker venom was specifically engineered to target the part of the brain that generates fear, creating terrifying hallucinations that can drive a person to madness. The images are bizarre and seem false afterwards, though they are vivid at the time. However, the hallucinations are not purely visual. They cause the victim to feel pain and other sensations that make the experiences realistic.
The barbed stinger should be dug out as soon as possible, which will minimize pain and accelerate healing. The crushed or chewed leaves of a particular plant can be placed on the stings to draw out the poison. Smoke can be used to sedate the tracker jackers and minimize the risk of being stung in the first place. This technique was used extensively by rebels when the wasps functioned as weapons.