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ACE Prep · Module 6 of 11

Ants

Quick answerUpdated September 24, 2026

What does ACE module 6 cover?

All ants are social insects with overlapping generations, adult care for young, and caste systems. The ACE exam tests species ID by anatomy and behavior, nesting habits, and control differences that stem from those differences.

Key factApproximate exam weight: ~8%.

Reviewed by LTK editorial team

Must-know facts

  • All ants are social: overlapping generations, cooperative brood care, caste systems, perennial nests.
  • Ant anatomy key ID points: number of petiole nodes (1 or 2), antennal club segments, presence of acidopore vs. sting, anal opening shape.
  • Subfamily Formicinae: single node, acidopore (round anal opening with fringe of hairs). Includes carpenter ants, crazy ants, rover ants.
  • Subfamily Myrmicinae: two nodes, sting. Includes fire ants, pharaoh ants, pavement ants, odorous house ants (note: OHA technically one node).
  • Carpenter ants (Camponotus): ¼–½ inch, polymorphic, single node, rounded thorax profile. Nest in hollow cavities above ground (trees, wall voids, doors). Produce frass (sawdust + insect fragments + pupal cases). Difficult to bait. Nocturnal.
  • Fire ants (Solenopsis invicta): 2-segmented antennal club, polymorphic, sting. Mound-builders in soil.
  • Pharaoh ants (Monomorium pharaonis): tiny (1.5–2 mm), light yellow, two nodes. Major hospital pest — can transmit Pseudomonas and Salmonella. Must bait ONLY — insecticide sprays cause budding.
  • Odorous house ants (Tapinoma sessile): single node hidden, smell like coconuts when crushed. Polygynous colonies. Very difficult to eliminate — perimeter baiting and exclusion.
  • Pavement ants: small, build soil nests under slabs, sidewalks. Two nodes. Often confused with other small ants.
  • Workers needed to identify most ant species — queens and males look alike across many species.

What the exam likes to ask

  • If an ant account keeps getting worse after insecticide treatment: suspect pharaoh ants or odorous house ants — switch to baiting only.
  • Carpenter ant frass contains insect fragments and pupal cases — this distinguishes it from termite frass.
  • Ants with two petiole nodes: typically Myrmicinae (fire ants, pharaoh ants, pavement ants).
  • Polymorphism (multiple worker sizes) = carpenter ants, fire ants, big-headed ants.

Field takeaways

  • Identifying the ant species before choosing a control method is the single most important step — wrong identification leads to wrong tactics.
  • Pharaoh ants can spread through hospitals via plumbing, electrical conduits, and wall voids — treatment must be comprehensive and bait-only.
  • Carpenter ant satellite colonies are common in structures — treat the satellite colony AND trace back to the parent colony.

Listen, watch, read

Podcast

Identifying Ants by Nodes and Antennae

Ant taxonomy using node count, antennae structure, and petiole shape — the diagnostic keys for field ID.

Slide deck · 13 slides

Ant Identification Field Guide

View the slides

Module 6 quiz

25 questions. Answer them all, then grade to see the reasoning.

  1. Q1Why does treating a pharaoh ant infestation with a repellent insecticide spray often make the problem worse?
  2. Q2Carpenter ant frass is distinguished from termite frass by
  3. Q3Which anatomical feature most reliably distinguishes an ant from a termite swarmer?
  4. Q4Which ant species requires identification of workers rather than queens for accurate species ID?
  5. Q5An odorous house ant infestation that keeps returning despite repeated treatments is most likely explained by
  6. Q6An ant has a single node and a round opening at the tip of the gaster ringed with short hairs. It belongs to the subfamily
  7. Q7Fire ants, pavement ants and pharaoh ants all share which feature?
  8. Q8Small dark ants trailing in a kitchen give off a smell like rotting coconut when crushed. The most likely species is the
  9. Q9A tiny yellowish ant has 10-segmented antennae ending in a two-segmented club. It nests outdoors and raids the brood of other ants. It is most likely the
  10. Q10A very small ant has a dark head and thorax but a pale, almost see-through gaster and legs. It is most likely the
  11. Q11An ant with two nodes, fine lengthwise grooves on the head and thorax, and a pair of short spines on the back of the thorax is pushing soil up through sidewalk cracks. It is most likely the
  12. Q12An ant that raises its heart-shaped gaster over its body when disturbed is most likely
  13. Q13A large ant with workers of several sizes has a single node and an evenly rounded, arched thorax when viewed from the side. It is most likely
  14. Q14A dark ant with extremely long antennae and legs runs in fast, erratic paths across a countertop. It is most likely the
  15. Q15After a 2010 revision, the tawny crazy ant and many other ants formerly placed in Paratrechina are now in the genus
  16. Q16A tiny brownish ant with nine-segmented antennae and no club, common in the South, is most likely the
  17. Q17Light-to-dark brown ants, all the same size, with a single upright node form wide, busy trails along a foundation. Colonies have many queens and nests seem to merge into one huge population. The most likely species is the
  18. Q18A sunny lawn has dome-shaped soil mounds with no central opening, and they explode with aggressive stinging ants of mixed sizes when disturbed. The most likely ant is the
  19. Q19A large red ant colony sits in a bare, cleared circle of ground with a single central entrance, and the workers sting painfully. It is most likely a
  20. Q20When is the best time to follow carpenter ant foraging trails back to the nest?
  21. Q21Ants are ignoring a sweet gel bait. What is the best next step?
  22. Q22What is the main advantage of a non-repellent liquid applied around a structure's perimeter for ants?
  23. Q23Some workers in a colony have enormous heads compared with the rest, and soil is pushed up along a patio edge. The ant is most likely a
  24. Q24In Florida, huge numbers of small black ants with pale yellowish feet trail along exterior walls. They have a single node, no sting and no noticeable odor. The most likely species is the
  25. Q25The widely recommended 'two-step method' for fire ants in lawns means

0 of 25 answered

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