Butterflies and Moths


We are observing small brownish moths in a client’s home, but we can’t determine where they are coming from.  They are not Indian meal moths, at first we thought they were clothes moths, but we can’t find any damaged fabric.

The pest you are dealing with is the brown house moth, (Hofmannophila pseudospretella). It is not a very common pest, but can be a nuisance.  This small moth ranges from 8.5mm (males) to 14.5mm (females) and has bronze colored wings covered with dark brown to black flecks.  The reason that you are not seeing any damage in fabrics is that it might not be feeding on fabrics.  The brown house moth has a wide range of foods that it will feed on including fabrics, seeds, processed grain, cereal, dead insects, dried flowers, furs and even dried bird or animal droppings.  The omnivorous feeding habit of this species is one of the reasons that it is so successful.

Controlling the brown house moth is similar to the strategies that might be employed to control other stored product or fabric pests.  Since we know what pest you are dealing with, the next step is to determine what it is feeding on.  Identifying the brown house moth’s food source can be tricky because it feeds on so many different things and it might be feeding (and breeding) in multiple places at the same time.  Start by checking the pantry for infested stored foods.  Since you had already ruled out the possibility of the Indian meal moth, you might have skipped a thorough inspection of this area.  In addition to cereals and processed grain products, inspect dried fruits and herbs for signs of moths or their larvae.  The pupae of the brown house moth will incorporate bits of their food into their silken cocoon, but a careful inspection will reveal their presence.  If you can’t identify an infestation in stored food products, inspect for alternative food sources such as animal hides, abandoned bird nests, dead insects inside wall voids, dried flower arrangements and other sources of food.  Once the breeding location is identified remove the food source, and treat the area with an appropriately labeled insecticide to control any larvae that might be hiding in cracks and crevices nearby.

I had a customer with a significant Indian meal moth infestation in their kitchen.  I am pretty confident that I located and removed all infested materials yet after a few days the moths appeared again; what’s happening?

Once the developing maggot has gotten its fill of the contents of your customer’s pantry, it leaves the food source to pupate elsewhere, often in cracks and crevices and behind frames and other wall-mounted items.  The pupal stage can go unnoticed depending on how well hidden it is, and although you might have made some crack and crevice treatments, or even physically removed some Indian meal moth cocoons, maybe one or two slipped by you.  You might want to try placing a pheromone trap in the area of the original infestation, and it wouldn’t hurt to conduct a re-inspection of foodstuffs and potential pupated sites while you’re at it.

I have been servicing a shipping facility that has been experiencing a major booklouse infestation.  They are so tiny and the facility is so large that it has been really difficult to determine where they are coming from.  When I put out sticky traps I seem to find them everywhere; what’s going on here?

The first and foremost thing to remember about booklice (pscocids), is that they have high moisture requirements, are tiny (1-2 mm), and typically feed on microscopic fungi.  Even if the warehouse has below 50% relative humidity, which is near the lowest level required for booklice to survive, there are likely microclimates throughout the facility that provide sufficiently humid conditions for them.  These pests are likely feeding on fungi growing unseen on cardboard, wooden pallets, or other receptive surfaces that absorb and retain moisture.  Fixing the humidity problem inside the warehouse is a great place to start and it’s recommended that you check out any materials that are entering the facility to see if the booklice are being brought in from the outside.