This tool is part of the Citrus Resource

Citrus Pests

 

Ants

 

Scientific name

 

Order Hymenoptera

Similar species

 

Ants are often mistaken for termites and earwigs. Each group can be easily distinguished by their antennae, body shape, and abdomen tip.

Ants Termites Earwigs
Body shape Waist (petiole) present Thick, elongate abdomen Thick, elongate abdomen
Antennae Elbowed (geniculate) Bead-like (moniliform) Thread-like (filiform)
Abdomen tip Stinger present Rounded, smooth tip Elongate, pincer-like; cerci present

Diagnostic characteristics

 
Nests
  • Several species with loose, dome-shaped, dirt, mound nests with no obvious entrance or exit.
  • Nests located in soil either in open, disturbed areas or at the base of tree trunks. Nests are also found around bricks, boards, rotting wood, refuse piles, bee hives, mulch, moist leaf litter, or bird nests.
  • During environmental stress, such as drought, some species invade homes or other buildings to establish a nest.
Adults
  • Smallest - 2.4 mm (0.12 in.).
  • Largest - 6 mm (0.24 in.).
  • Body size varies. There can be worker ants of multiple sizes within a single colony.
  • Brick red to honey brown. Several species with a black gaster (last abdominal segment)
  • Stinger at the tip of the gaster.
  • Hairy to nearly smooth body.
  • Two pairs of long, narrow wings briefly present in unmated, reproductive individuals.
  • Male wings with a stigma (small colored area near the wing tip).
  • Multi-segmented geniculate (elbowed) antennae occasionally with a clubbed tip.
  • Chewing mouthparts with variation in the number of teeth (denticles) present on the mandibles.
  • Compound eyes and simple eyes (ocelli) present.
  • Tarsi have 5 segments.
  • Waist (pedicel) with either 1 or 2 segments.
Pupae
  • Smallest size - 2 mm (0.09 in.).
  • Largest size - 3 mm (0.12 in.).
  • Females smaller than males.
  • Located in underground nest, only seen when mound is disturbed.
  • Closely resemble adults with legs and antennae held close to body.
  • Initially white with black eye-spots but darken with age.
  • Body appendages are free and not fused to the body.
Larvae
  • Smallest size - 1.7 mm (0.07 in.).
  • Largest size - 2.5 mm (0.1 in.).
  • Females smaller than males.
  • Four larval instars.
  • White to cream-colored.
  • Legless and grub-like, cared for by workers.
  • Found in underground nest, only seen when mound is disturbed.
Eggs
  • Smallest size - 0.20 mm (0.00 8in.).
  • Largest size -0.30 mm (0.01 in.).
  • Translucent to white.
  • Ovoid in shape.
  • Found in underground nest, only seen when mound is disturbed.

Hosts

 
Citrus hosts

All citrus species and their hybrids. Ants are often not a direct pest but disrupt agricultural production by preventing effective use of biological controls, killing pollinators, and plugging irrigation lines.

Non-citrus hosts

Not a direct pest but is disruptive in agricultural production in general.

Host damage

 

Not typically a direct pest but is disruptive in agricultural production in general.

Flowers
  • Feed on flowers.
Fruit
  • Feed on young, developing fruit.
Trunk
  • Chew on the bark and cambium of young trees to feed on sap.
  • Can girdle and kill young trees.
Twigs
  • Chew twigs of newly-planted, young trees.
  • Chew off new growth.
Other
  • May not damage citrus or crops directly.
  • Can destroy beehives.
  • May nest in and plug irrigation lines.
  • Protect honeydew-producing insects and, thus, interfere with the biological control of scales, whiteflies, and aphids.
  • May preferentially attack some parasitized pest species, resulting in disruption of biological control programs of pest species.
  • Leaf-cutting ants can cause significant defoliation.

Biology

 

Ant colonies have a caste system, an organization of specialized groups within the colony consisting of the queen (or queens), large workers (major workers), many medium sized workers (media workers), and a majority of small workers (minor workers). The queen is the single producer of eggs while all worker types are sterile females. Foraging workers perform tasks like collecting honeydew and seeds. Worker ants are fast moving and initially feed young larvae with a liquid diet. After the fourth instar, larvae are fed solid food, rich in protein. Larvae secrete digestive enzymes to break down the solid food and regurgitate it back to worker ants (which can only take in liquids).

Ants congregate in high densities in citrus orchards and other human-modified agricultural systems. Species like the red imported fire ant are highly aggressive, out-compete other ant species for resources, or can establish independent colonies by having multiple queen forms. Other species like the Argentine ant lack aggression among other colonies of the same species. Over time, colonies can cooperatively develop a large "supercolony."

High humidity and sustained free water are ideal conditions for ant colonization. Ants suspend foraging at hot temperatures.

References

 

Bambara, S., M. Waldvogel, J. Silverman, and J. Brightwell. 2006. Argentine ants in the landscape and in the home. North Carolina State University - Department of Entomology. Extension Publication ENT/ort-140. (http://www.ces.ncsu.edu/depts/ent/notes/O&T/trees/note140/note140.html).

Collins, L. and R. Scheffrahn. 2001. Featured Creatures: Red imported fire ant, Solenopsis invicta Buren (Insecta: Hymenoptera: Formicidae: Myrmicinae). University of Florida - Department of Entomology. Extension Publication EENY-195. (http://entnemdept.ifas.ufl.edu/creatures/urban/ants/red_imported_fire_ant.htm).

Cook, J.L. S.F. Austin, S.T. O'Keefe, and S.B. Vinson. 2002. Texas fire ant identification: An illustrated key. Texas Cooperative Extension Fire Ant Plan Fact Sheet 013. (http://fireant.tamu.edu/materials/factsheets_pubs/pdf/fapfs013.2002rev.pdf).

Davies, F. and L. Jackson. 2009. Pest disease and weed management for the bearing grove, pp. 204-221. In Citrus growing in Florida. 5th ed. University Press of Florida. Gainesville, Florida.

Triplehorn, C. and N. Johnson. 2004. Hymenoptera pp. 481- 487. In Borror and DeLong's Introduction to the study of insects. 7th ed. Brooks/Cole Cengage Learning. Belmonte, California.

Sarnat, E. 2008. Pacific invasive ant key: Identification guide to invasive ants of the Pacific islands. USDA APHIS PPQ CPHST Identification Technology Program and University of California Davis. (http://itp.lucidcentral.org/id/ant/pia/index.html).

Authors

 

Guerrero, S., J.A. Weeks, and A.C. Hodges

 

Citrus Pests
Content last updated June, 2012
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