The term “orange ants” is a common designation used to categorize several distinct ant species that exhibit hues ranging from pale yellow to reddish-brown. This name does not refer to a single biological classification but rather a group of ants with lighter pigmentation in their exoskeletons. This light-colored cuticle makes them distinct from the more common black or dark brown ant varieties. Identifying the specific species requires examining physical characteristics and nesting habits, as “orange” is a visual umbrella for multiple types of insects.
Common Species of Orange Ants
Two frequently encountered species fitting the orange or yellow description are the Citronella Ant and the Pharaoh Ant. Citronella ants, sometimes called larger yellow ants, are robust, with workers typically measuring between one-eighth and three-sixteenths of an inch in length. Their coloration ranges from golden yellow to yellowish-brown, and they possess a distinctive, segmented body structure with bent antennae.
Pharaoh ants (Monomorium pharaonis) are considerably smaller, often measuring only one-sixteenth to one-eighth of an inch long. These minute insects are usually light yellow to reddish-brown, often with a slightly darker abdomen. The Pharaoh Ant worker has a two-segmented petiole, or waist, which differs from the Citronella Ant. They also have a three-segmented club at the end of their twelve-segmented antennae.
Habitat and Behavioral Characteristics
Citronella ants are primarily subterranean, constructing colonies in moist soil, often beneath stones, logs, or concrete slabs. Their presence is frequently indicated by small mounds of excavated soil near foundations or in lawns. These ants are not considered traditional household pests because workers rarely forage inside buildings, focusing instead on their specialized diet.
The specialized food source for Citronella ants is honeydew, a liquid they collect from subterranean aphids and mealybugs feeding on plant roots. Humans mostly observe them when winged reproductive swarmers emerge from the ground, often entering homes through foundation cracks during late spring or early summer. A unique defensive trait is the strong, lemon or citronella-like odor they emit when crushed or alarmed.
Pharaoh ants thrive in warm, humid interior environments like hospitals, grocery stores, and residential kitchens. Their nests are typically located in inaccessible spots such as wall voids, behind baseboards, under floors, or within furniture and appliances. They are opportunistic feeders, consuming sweets, proteins, and fats, which makes them a persistent indoor pest.
A primary characteristic of Pharaoh ants is their ability to “bud,” where a portion of the colony splits off to form a new colony when disturbed. This budding behavior, often triggered by repellent pesticides, allows infestations to spread rapidly throughout a structure. Due to foraging in unsanitary areas, these ants can mechanically transmit pathogens, presenting a public health concern in institutional settings.
The Biological Basis of Orange Coloration
The orange or yellow coloration in these ant species results from pigments known as carotenoids, which the ants do not synthesize themselves. Like most animals, ants must obtain these yellow, orange, or red organic compounds directly from their diet. Carotenoids are tetraterpene pigments produced by plants, algae, fungi, and bacteria. Specific carotenoids, such as xanthophylls, are deposited into the ant’s exoskeleton, resulting in the visible orange hue. In Citronella ants, this pigmentation is strongly linked to their diet of honeydew, a substance rich in compounds produced by root-feeding insects.