So what are they, and what do they want?
The “Phereoeca uterella”, also known as “plaster bagworm”, is a type of moth. It is often mistaken for the “Phereoeca allutella”, or “household casebearer”, which is of a different moth family but similarly has an awesome common name.
The oval-shaped “bags” you see are actually the larvae of the plaster bagworm, enclosed rather snugly in their protective case made of lint, silk fibres and other debris, as they make their way around your home, foraging for food.
The bugs like to feed on dust, spiderwebs, hair, soil, dead insects, lint, wool, fabric made of organic fibres, and even discarded larval cases of their own species.
Naturally, they are attracted to spaces in your home with plentiful food supply and minimal disturbances. And – unlike most Malaysians – plaster bagworms flourish under highly humid conditions.
The male will eventually emerge as moths and abandon their case, which explains the “empties” you might come across in your house. The female adults, on the other hand, do not grow wings and will keep their cocoons.
The adults eventually mate, and the female can produce up to 200 light-blue eggs, which are deposited in her case. Ever so tragically, both partners die after mating.
A complete cycle from egg to adult takes about two and a half months.
Now, if you find these little winged wonders in your home, should you get rid of them, or is peaceful coexistence an option?
While they are harmless as they don’t bite or sting, an infestation could occur if left unchecked – meaning they will feed on your rugs, clothes, and other fabrics made of natural fibres. They tend, however, to give cotton apparel a miss.
Still, these bugs aren’t terribly picky eaters, which is a cause for concern. So, how do you get rid of them?
One way is by using a vacuum cleaner, though it might get tricky getting to the ones in mid-air or located in hard-to-reach corners. Be sure to immediately empty the vacuum bags outside your house or they might escape!
If you’re not squeamish, you could gather them with your hands or using sticky tape. Some people choose to submerge them into a bucket of soapy water – or even flush them down the toilet bowl for good measure.
Pest prevention
It’s a good idea to clean your home often, and especially to get rid of all traces of dust and spiderwebs. Pay particular attention to your less-accessible nooks and crannies, where darkness and moisture might be prevalent.
As plaster bagworms thrive in humid spaces, using the air conditioner could help lower the moisture content in the air.
Alternatively, ensure good circulation by opening your windows and leaving your fans running. (Then arises the question of energy conservation and carbon footprint, but perhaps it’s best to tackle one problem at a time.)
Should the infestation be more serious, you could use the time-honoured method of insecticide, natural or otherwise. And, for severe cases, you might want to enlist the help of pest-control professionals.
The fact that the plaster bagworm can fly and breed in large numbers means they can easily spread. But how did they get into your house in the first place?
Well, you might have brought the problem on yourself by inadvertently bringing infested items into your residence.
In all likelihood, though, the moths simply flew into your home, enjoyed the conducive conditions, and decided to stay, making them a most definitively unwelcome – and destructive – houseguest.