Paratrechina longicornis is an ant species that invades homes in large numbers where it feeds on human foods and occasionally nests within moist and rotten woodwork. This ant species is more commonly known as the longhorn crazy ant, not to be confused with the invasive Tawny crazy ant found in the southeastern states. The longhorn crazy ant is a non-native ant pest that is considered invasive in Massachusetts.

Longhorn crazy ant workers are relatively small at 2.3 to 3 mm in length, but their tremendously long antennae makes them easy to recognize when viewed up close. Also, much like their invasive relative down south, longhorn crazy ants move erratically, which makes them recognizable without the aid of magnification. These ants are mostly black or dark brown in color, and they are sometimes referred to as black crazy ants to avoid confusion with other crazy ant species of different colors.

In tropical and subtropical areas the longhorn crazy ant can be an agricultural pest and house pest, but in temperate areas like Massachusetts they are pervasive indoor ant pests that are commonly managed by pest control professionals. Since these ants are accustomed to living indoors with humans, there is no northern limit to their distribution, as they can be found in much of eastern Canada as well. Many entomologists consider the longhorn crazy ant to be the most widely distributed ant species in the world, but other experts counter that the Pharaoh ant is probably found in more countries.

The longhorn crazy ant has been found infesting the top floors of high rise buildings in Boston including hotels and office buildings. Workers will readily eat most food crumbs they encounter within homes and buildings, but their diet preferences vary by season. For example, workers will readily eat high protein foods during the summer, but they only seem to consume sugar-rich foods during the fall and winter. Because of this, workers avoid baits during the summer months. Workers can establish nests in just about any location including both moist and dry locations. Most infestations see workers enter homes from nests in soil located against housing foundations, but they are often found nesting in wall voids and damp wood as well.

Have you ever found ants in your home that moved erratically?