Questions to ask customers to confirm and then manage a webbing clothes moth infestation.
Webbing clothes moth adult, larvae and pupal case on felt (photo: Patrick Kelley, Insects Limited, 2012).
This sentence is often the beginning of many phone calls from distraught people wanting assistance with their potential pest issue. As a pest management professional, there are several bits of key information that you need to gather from this caller to begin the process of solving their problem. Let’s look at what it takes to figure out a clothes moth infestation and how we can gather that information. Here are the questions you should be asking:
1. Are you seeing any actual insects or simply the holes? This question needs to be asked to determine if insects are actually involved in the damage. Believe it or not, many holes in clothing are mechanically generated from people rubbing against sharp metal edges in their day-to-day work spaces and not even knowing it. If the holes in their clothing do not have evidence of insect frass, cast skins or larval webbing and all of the holes are occurring in similar areas of the body (e.g., stomach or side) then they are probably mechanical in nature. Although this mechanical damage occurs quite often, people want something other than themselves to blame the holes on. Good luck getting them to agree with you that they made the holes themselves! If insects did create the damage on the clothing and the clothes have not yet been cleaned, you will find pest evidence around the hole.
2. Can you describe the insects that you are seeing around the problem area? Assuming they are seeing insect activity, you need to determine if the damage is from carpet beetles or clothes moths. A series of questions is necessary in order to get solid information. Can you describe the insects you are seeing? Are they flying? Do they have a hard shell (beetle) or are they just very small moths? Varied carpet beetles and black carpet beetles also can damage clothing and rugs just like clothes moths. A big difference is the carpet beetles leave their larval cast skins behind in large numbers around the area of damage. Clothes moths, on the other hand, will leave their peppery-looking frass, wispy larval webs and pupal cases around the damage. Carpet beetles are attracted to light and the adults often can be found around sunlit windows if they present. Clothes moths are not attracted to light.
3. Are the wings of the moths all one solid color?
|Casemaking clothes moth (Tinea pellionella) damage. Photo: University of Georgia Archive, University of Georgia, Bugwood.org.
So you have narrowed it down to the fact the caller does have moths that are damaging their clothing or rugs. The next bit of information we need to find is what species are we dealing with? There are two prevalent species of clothes moths worldwide. These are webbing clothes moths and casemaking clothes moths. Although they are similar in size, webbing clothes moth adults can be identified by the fact they have absolutely no dark markings on the wings. These moths are a solid gold/buff color throughout their wings and body with a slightly orange tuft of hair on their heads. Casemaking clothes moths, on the other hand, are darker in color with three dark spots on each wing. Another clue is that webbing clothes moths will entwine their pupal cases (cocoons) right into the clothing they are feeding on.
4. What can I do now to get rid of them? We now know that the caller has clothes moths and we have even figured out the species. The next step in management of this pest is locating the sources of infestation and removing them or treating them. Pheromone traps are available for both of these species of clothes moths and they can be extremely helpful in locating these sources and determining if the treatments have worked. When the pheromone traps direct your attention to a specific area, a visual inspection is necessary to find the infested articles of clothing or rug. Look for adult moths on the walls and look for pupal cases, larvae, webbing and frass on the clothing or rugs. Once you find the activity, the item should be bagged and sealed to prevent further spread. If the infested item has a low value, it can be thrown away outside. If it is something they want to save, there are a few options for treatment. These include:
- Leave the sealed item in the freezer for at least two weeks. Freezing kills all stages of moths.
- Run the item through the hottest cycle of the clothes dryer for one hour. Heat kills all stages of moths.
- If the item is a rug, a water-based and labeled residual insecticide can be used. Note: Check a small area of the rug first for staining or color running. It is recommended to treat both sides of the rug. Do not spray any clothing with a pesticide!
- Fumigation with phosphine or sulfuryl fluoride gas will penetrate any clothing or rugs and kill all stages of the insect. This should only be performed by licensed and qualified fumigators. Standard pesticidal foggers alone will generally not eliminate the problem.
A Pest on the Rise. Like bed bugs, clothes moths are gaining stature throughout the world. This could be caused by a rise in temperatures, more natural fibers in our closets or their ability to live side by side with people. It is important to understand what the insect is and how to stop them from causing damage.
The author is vice president of Insects Limited, Westfield, Ind., and can be contacted at firstname.lastname@example.org.