How to Identify Indoor Insects by Droppings

Written by kimm hunt
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How to Identify Indoor Insects by Droppings
Roach frass and secretions pose a health hazard in the home. (Jupiterimages/Comstock/Getty Images)

If you have visible insect droppings in your home, you may have a pest infestation. Insect faeces, or frass, are so small that only a substantial accumulation will be noticeable. This indicates that a large numbers of insects are present. You can identify five common household pests by their frass: Cockroaches, fleas, bed bugs, carpenter ants and termites.

Skill level:
Moderately Easy

Things you need

  • Sheet of white paper
  • Few drops of water

Show MoreHide


  1. 1

    Determine where the frass is visible. Different insects have different habits. Roach frass accumulates along bare wooden surfaces, paper and cardboard in rooms that provide a water source, such as kitchens and bathrooms.

    Flea dirt collects on pet bedding and other areas where the pet rests, and on the pet itself, particularly near the skin of the lower abdomen. Bed bug frass is visible on bed linens.

    Carpenter ant and termite frass accumulates in basements, crawlspaces and attics near exposed wooden beams.

    How to Identify Indoor Insects by Droppings
    Termite and carpenter ants live in wood. Their frass is found near exposed beams. (Brand X Pictures/Brand X Pictures/Getty Images)
  2. 2

    Note the amount, size and colour of the faeces. Roach frass looks small black specks, or black pepper flecks. It will be spread out along the roach runway, a frequently-travelled path all the roaches in a colony will use.

    Flea dirt consists of small, deep maroon or black flecks that are very hard and dry to the touch. Bed bug frass is similar and will appear as small reddish-brown spots that look like rust.

    Carpenter ant frass is usually seen in the sawdust piles that collect outside the nest. The sawdust pile itself is the best indicator of carpenter ants, but tiny black dots visible in the dust are fecal material.

    Termites leave six-sided round pellets the size of poppy seeds. Their colouring is similar to that of the wood they have consumed. The colour can vary from grey to various shades or brown. Mud tubes, composed of soil, termite faeces and saliva, are a sure sign of termites. Look for these hanging like stalactites from floor joists and running between floor joists and small openings to the exterior.

  3. 3

    For flea and bed bug frass, place a piece of the suspected the droppings onto a white piece of paper. Add a drop of water. If it is flea or bed bug faeces, the water will turn red because these bugs feed exclusively on blood.

Tips and warnings

  • There are hazards associated with each of these insect pests. Roaches can cause respiratory problems and may transmit diseases such as salmonella and hepatitis. Termites and carpenter ants can cause severe structural damage to homes. Fleas and bed bugs leave itchy welts that can become infected.

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