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ACE Prep · Module 10 of 11

Stored Product Pests

Quick answerUpdated September 24, 2026

What does ACE module 10 cover?

Stored product pests infest dry goods, grain products, and natural materials. They are divided into primary pests (infest whole grains) and secondary pests (infest damaged or processed products). Control requires thorough source inspection and sanitation before any chemical application.

Key factApproximate exam weight: ~8%.

Reviewed by LTK editorial team

Must-know facts

  • Primary pests infest whole, undamaged grain internally. Examples: Angoumois grain moth (Sitotroga cerealella), weevils (Sitophilus granarius/oryzae), lesser grain borer.
  • Secondary pests infest damaged, processed, or milled grain. Examples: flour beetles (red/confused), Indian meal moth, saw-toothed grain beetle, cigarette beetle, drugstore beetle.
  • Indian meal moth (Plodia interpunctella): most common stored product moth. Pheromone traps available. Silk webbing associated with infested food. Nocturnal, attracted to lights. Primary secondary pest.
  • Angoumois grain moth: primary pest, feeds internally in whole grain. No silk associated externally.
  • Flour beetles (Tribolium confusum = confused; T. castaneum = red): reddish-brown, secondary pests. Red flour beetle has clubbed antennae (3 segments); confused flour beetle antennae gradually enlarge.
  • Cigarette beetle (Lasioderma serricorne) and drugstore beetle (Stegobium paniceum): both infest a wide variety of dry goods (dried herbs, tobacco, pet food, books). Nearly identical — drugstore beetle has striated elytra.
  • Dermestid beetles (Dermestes/Trogoderma): warehouse beetle larvae are hairy with 2 hooks at end of body, ~½ inch.
  • Physical control: heat (120°F/60 min kills all stages) or cold (-4°F for 7–14 days). Heat is most reliable for structures; cold for individual packages.
  • Key control elements: inspection + ID, sanitation, rotation of goods (FIFO), exclusion, physical controls, then chemical if needed.
  • Hidden sources of infestation: pet food, organic fertilizers, potpourri, old rodent baits, dried flowers, food in coat pockets, bird/rodent/bee nests.

What the exam likes to ask

  • Indian meal moth = secondary pest with silk; Angoumois grain moth = primary pest, no silk externally.
  • Beetles with clubbed antennae: warehouse beetle, confused flour beetle, drugstore beetle — all share this character.
  • All beetles have complete metamorphosis — egg, larva, pupa, adult.
  • Temperature treatment works for stored product pests: 120°F/60 minutes or -4°F/7–14 days.

Field takeaways

  • Always find and dispose of the infested source before applying insecticides — otherwise the infestation continues from the source.
  • Hidden sources (pet food, old rodent bait, dried herbs in a cabinet) are commonly overlooked. Check everything.
  • Pheromone traps are excellent monitoring tools for stored product moths and some beetles — they catch pests and tell you which direction infestation is spreading.

Listen, watch, read

Podcast

How Humans Evolved the Perfect Pantry Pest

Stored product pest biology, co-evolution with human food storage, species ID, and IPM control strategies.

Podcast

The Biological Battleground in Your Pantry

Stored product pest competition, secondary infestations, monitoring with pheromone traps, and heat/cold treatments.

Slide deck · 15 slides

ACE Stored Product Dossier

View the slides

Diagnostic Taxonomy: Lookalike Stored Product Pests

8:23

The Pantry Private Eye

8:00

Module 10 quiz

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

  1. Q1Silk webbing and frass in the top layer of a bag of birdseed point most strongly to which pest?
  2. Q2A larva covered in long bristly hairs is found in a pet food storage room. Which beetle family is it most likely from?
  3. Q3Which stored product pest develops inside individual whole kernels, so an infestation is often missed until adults emerge?
  4. Q4Extension guidance for heat-treating a small infested food package at home is to hold it at about
  5. Q5The FIRST step in controlling a stored product pest infestation is
  6. Q6A snout beetle from a bin of whole wheat cannot fly, has elongated pits on the pronotum and no light spots on its wing covers. It is most likely the
  7. Q7Whole grain kernels with small, neat, round exit holes most strongly suggest
  8. Q8A tiny humpbacked beetle with its head tucked under has smooth wing covers and saw-toothed antennae. It is most likely the
  9. Q9Small, light-brown, humpbacked beetles are flying around a home kitchen. What is the most productive first step?
  10. Q10A flat, slender, brown beetle with six tooth-like projections along each side of the thorax is found in oatmeal. It is most likely the
  11. Q11Two reddish-brown flour beetles look alike. One has antennae ending in an abrupt three-segmented club; the other's antennae thicken gradually toward the tip. The first one is most likely the
  12. Q12Freezing is a common non-chemical way to disinfest small packages of stored food. Extension guidance generally recommends
  13. Q13A small moth has front wings that are pale grayish-tan near the body and coppery reddish-brown on the outer part. It is most likely the
  14. Q14Pheromone traps used to monitor Indian meal moths catch mainly
  15. Q15Silken cocoons are found where the wall meets the ceiling, several feet from an infested pantry. What best explains this?
  16. Q16In a flour mill, larvae spin so much silk that they clog machinery. The adults are gray moths with wavy black lines across the front wings. The pest is most likely the
  17. Q17Small buff moths with narrow, heavily fringed, pointed hind wings are emerging from a decorative ear of dried corn. They are most likely
  18. Q18Which Trogoderma species is a serious quarantine pest that U.S. inspectors watch for at ports of entry?
  19. Q19Dark beetles with a pale band across the front half of the wing covers, dotted with dark spots, appear in a home where a mouse recently died in a wall. They are most likely
  20. Q20A golden-brown, carrot-shaped larva with a long tuft of hairs at its tail end is found under a wool rug. It is most likely a
  21. Q21A small, evenly golden moth with a tuft of reddish hairs on its head shies away from light, and silk tunnels are found on a wool coat. It is most likely the
  22. Q22During a humid summer, tiny pale, soft-bodied insects appear in damp stored papers and on cereal boxes. Which response targets the cause?
  23. Q23Thousands of tiny reddish-brown beetles appear in a newly built home with no infested food in it. They are most likely
  24. Q24A small beetle with a shiny, globe-shaped body and long legs, which looks like a tiny spider, is scavenging in a cool storeroom. It is most likely a
  25. Q25Stored dried beans have round holes, and the small, stout beetles found with them have no long snout. They are best described as

0 of 25 answered

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