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Citrus

Ants and Their Damage

On this page
Ant damage
  • Sooty mold
  • Ants tending soft scale
  • Crater surrounding nest entrance
Major pest ants
  • Argentine ant
  • Native gray ant
  • Southern fire ant
  • Red imported fire ant
Other ants in citrus
  • Bicolored pyramid ant
  • California harvester ant
  • California rainbow ant
  •  
  • Pavement ant
  • Small honey ant
  • Thief ant

Names link to more information on identification and management.

Click on photos to enlarge
Ant damage
Sooty mold
Sooty mold
Identification tip: Blackish fungi grow on fruit and leaves when ants increase the abundance of phloem sap-sucking Homoptera, including aphids, mealybugs, soft scales, and whiteflies.

Ants tending brown soft scale
Ants tending brown soft scale
Identification tip: Trails of ants with swollen abdomens often indicate that ants are feeding on honeydew-excreting insects. Ants attack natural enemies that otherwise help to control these pests.

Crater surrounding a nest entrance
Crater surrounding a nest entrance
Identification tip: Ants pile excavated soil outside their underground nests. Some ants can bite or sting or strip bark from young trees.

Major pest ants

Argentine ant, Linepithema humile (=Iridomyrmex humilis)

Argentine ant worker
Argentine ant worker
Identification tip: Workers are uniformly light to dark brown, about 0.09 to 0.1 inch (2.2–2.6 mm) long.

Argentine ant
Argentine ant
Identification tip: Adults have 12 antennal segments and no distinctly swollen terminal segments (no "club"). They have one-segmented petioles and their thorax is uneven in shape when viewed from the side.

Argentine ants tending scale
Argentine ants tending scale
Identification tip: If carefully observed, honeydew-feeding ants can be seen stroking individual aphids, mealybugs, soft scales, or whiteflies. Ants feed on the sweet sugary liquid these pests excrete.

Native gray ants, Formica species

Native gray ant worker
Native gray ant worker
Identification tip:  Adults are about 0.1 to 0.2 inch (2.5–4.5 mm) long and variably colored, typically a mix of grey to dull brownish. They move fast in irregular patterns and usually forage individually, not in dense trails of ants.


Native gray ant
Identification tip: Gray ants have 12 antennal segments with no club. They have one-segmented petioles.

Ants tending mealybugs
Ants tending mealybugs
Identification tip: Gray ants feed on insects and sweet liquid excreted by pests such as these mealybugs.

Southern fire ant, Solenopsis xyloniTop of page

Southern fire ant worker
Southern fire ant worker
Identification tip: This native ant varies in size from about 0.07 to 0.2 inch (1.6–5.8 mm) long. Workers are bicolored with a yellowish red head and thorax and a dark gaster (swollen part of their abdomen).

Southern fire ant
Southern fire ant
Identification tip: Adults have 10 antennal segments with a two-segmented terminal club. They have a two-segmented petiole, and often sting when disturbed.

Southern fire ant nest
Southern fire ant nest
Identification tip: Workers are usually the only stage observed above ground. Digging beneath entrances to their underground nests will reveal pale pupae and larvae, reproductives (which may have wings), and more worker ants.

Red imported fire ant, Solenopsis invicta

Red imported fire ant
Red imported fire ant
Identification tip:  Workers are mostly dark reddish brown. This exotic, invasive species is extremely aggressive. It attacks in large numbers and readily stings when disturbed.

Red imported fire ant
Red imported fire ant
Identification tip: Adults have 10 antennal segments with a two-segmented club. They have a two-segmented petiole.

Red imported fire ant
Red imported fire ant
Identification tip: Fire ants are variable in size, with workers in the same trail ranging from about 0.07 to 0.2 inch (1.6 to 5 mm) long.

Other ants in citrus

Bicolored pyramid ant, Dorymyrmex (=Conomyrma) bicolor

Bicolored pyramid ant
Bicolored pyramid ant
Identification tip:  Workers have an orange or reddish brown head and thorax and darker brownish black gaster (swollen part of their abdomen). Workers are about 0.08 to 0.1 inch (2–3 mm) long, fast-moving, and usually travel in trails.

Bicolored pyramid ant
Bicolored pyramid ant
Identification tip: They have 12 antennal segments with no club. Adults have a one-segmented petiole and a small pyramid-like projection on the posterior dorsal surface of the thorax.

Bicolored pyramid ant
Bicolored pyramid ant
Identification tip:  Workers feed on honeydew and insects.

California harvester ant, Pogonomyrmex californicusTop of page

California harvester ant
California harvester ant
Identification tip: Workers are  about 0.22 to 0.4 inch (5.5–8.7 mm) long and reddish brown.

California harvester ant
California harvester ant
Identification tip:  Adults have a two-segmented petiole and can sting. Pogonomyrmex means “bearded ant,” so called for the fringes of long hairs located behind the mouthparts.

California harvester ant nest
California harvester ant nest
Identification tip: Their mounds are often cleared of surrounding vegetation and littered with seed husks and other plant debris.

California rainbow ant, Iridomyrmex (=Forelius) pruinosus

California rainbow ant
California rainbow ant
Identification tip:  Workers are about 0.07 to 0.1 inch (1.8–2.5 mm) long and vary in color, from yellow to light brown. Workers form conspicuous trails.

California rainbow ant
California rainbow ant
Identification tip: Adults have 12 antennal segments and no distinct terminal club. They have a one-segmented petiole. When crushed they emit the odor of rotten coconut, an unpleasant odor resembling rancid butter.

 

Pavement ant, Tetramorium caespitum

Pavement ant
Pavement ant
Identification tip:  Workers vary in color from brown to black, and are about 0.1 to 0.13 inch (2.5–3 mm) long. The top surface of their head and thorax is sculptured with many parallel grooves.


Pavement ant
Identification tip:  Adults have 12 antennal segments with a three-segmented club. They have a two-segmented petiole and a pair of spines behind the thorax.

Pavement ant nests
Pavement ant nests
Identification tip:  Their conspicuous piles of excavated soil often occur in clusters. They also nest hidden under stones, wood, and other debris on the ground.

Pyramid ant, Dorymyrmex (=Conomyrma) insanusTop of page

Pyramid ant
Pyramid ant
Identification tip: Workers are uniformly brown, and about 0.6 to 0.08 inch (1.5–2 mm) long. Individuals are somewhat smaller in comparison with the similar bicolored pyramid ant.

Pyramid ant
Identification tip: Workers have 12 antennal segments with no club. They have a one-segmented petiole and pyramid-like projection on the top rear surface of the  thorax.

Pyramid ant nest
Pyramid ant nest
Identification tip: Nests are typically located in dry, open areas. Crater-like excavations surround a single entrance.

Small honey ant, Prenolepis imparis

Small honey ant
Small honey ant
Identification tip:  Workers are shiny and vary in color from light to dark brown or black. They are about 0.08 to 0.2 inch (2–4 mm) long. Their gaster (the swollen rear part of the abdomen) is triangular in shape.

Small honey ant
Small honey ant
Identification tip:  Adults have 12 antennal segments with no club, and a one-segmented petiole.

Small honey ant
Small honey ant
Identification tip: Workers feed above ground during cool weather. During hot weather they spend up to several months continually below ground in nests that are often many feet deep.

Thief ant, Solenopsis molesta

Thief ant
Thief ant
Identification tip: Workers are yellow or light brown to dark brown and very small, about 0.06 to 0.09 inch (1.5–2.2 mm) long.

Thief ant
Thief ant
Identification tip:  Adults have 10 antennal segments with a two-segmented club. They have a two-segmented petiole.

 

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