Insect spray advert falsely warns about 'health risk of household moth' in Malaysia

“Be careful if you find this insect ... If upon touching, the skin will be swollen, itchy and painful for days,” reads a Malay-language Facebook post shared on November 7, 2023. 

The false post included several photos of a common moth known as a household casebearer alongside images of insect bites and stings.

It linked to a spray available on an online shopping platform that it claimed was "the only way to get rid of insects" in Malaysia.

Image

Screenshot of the false post, captured on January 17, 2024

The same claim with the product link was also shared here on Facebook. On TikTok, the spray has been advertised for almost two years alongside a similar claim here, here and here. 

However, experts told AFP that household casebearers do not generally cause skin irritation or health problems.

AFP also found the photos used in the post were stock images unrelated to the moths.

No threat to humans

Entomologists told AFP the insect shown in the false posts is a type of moth called the household casebearer (Phereoeca uterella), also known as the “plaster bagworm” (archived link). 

Norhisham Razi, a senior lecturer at Universiti Putra Malaysia's Department of Forestry Science & Biodiversity, told AFP the household casebearer is "unlikely to be the cause of insect bites" and is not known to cause skin irritation directly (archived link). 

Abdul Hafiz Ab Majid, an entomologist and associate professor at Universiti Sains Malaysia's School of Biological Sciences, also said that the moths do not pose a direct threat to humans and they "do not bite humans or transmit diseases" (archived link). 

But, he said, they can be a nuisance if your home becomes infested with them, causing damage to clothes, fabric-based furniture, carpets, or other items.

"However, the damage is generally limited to the affected materials and does not have any significant health implications," he told AFP on January 11, 2024.

Unrelated photos 

Reverse image searches on Yandex and Google found the posts shared stock photos used to illustrate bites and stings from an array of insects and arachnids, but not from the household casebearer.

The first image has been used – for example, here and here – in Russian-language articles about mosquito bites (archived links here and here).

The second image has been shared in articles written in various languages that state the skin irritation was caused by insects and arachnids including wasps and scorpions (archived links here and here). 

AFP traced the third image to a Russian-language website which stated it shows a bed bug bite (archived link). 

Below are screenshot comparisons of the images in the false post (left) and the generic photos published by various websites (right):

Image

Screenshot comparison of the images in the false post (left) and the generic photo published by various websites (right)