Freaking huge moths have been making their presence felt in Singapore this year.

Known as Lyssa zampa, these brown-greyish, 16cm-long, nocturnal, white-striped moths also known as the "Tropical Swallowtail Moth", have been clinging to walls and flying into people's faces.

Very few things are known about them, such as how they are attracted to urban lights even as they breed in forested areas and its caterpillars feed on the leaves of Endospermum, a tree from the rubber family.

Other than that, precious little is known about this elusive species even though they are native to Singapore and Southeast Asia and have been making an appearance once every few years.

Here are four things we still do not know about the giant moths:

1. No one's quite sure why they only show up three to four months in the middle of each year

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Ecologists are puzzled as to why the moths are more commonly seen between May and August every year. It has been noticed that they breed and spawn more during this period but no one is quite sure why.

It is also not known if their breeding ground is evenly distributed across Singapore or concentrated in a few areas with more vegetation.

2. This year's population explosion is unaccounted for

Source: Clarence Ching

One explanation why there are so many moths now is that there is a higher nectar abundance due to mass flowering of plants earlier this year. This increases butterfly and moth populations and might have contributed to the tropical swallowtail moth's population boom.

However, there was also a population boom in 2005 but there was no mass flowering then.

No one knows how or why this seasonal fluctuations occur or if this seasonal emergence is typical of populations elsewhere.

But one other possible reason for this boom could be due to the decline in natural predators. The moth numbers have peaked with the end of bird migration season from September to March, said butterfly expert Khew Sin Khoon, an honorary research affiliate at the Lee Kong Chian Natural History Museum.

3. Sightings of the giant moth in Singapore are not evenly distributed

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The giant moths might be all over Singapore, but not everyone has seen it. Yet.

And even though the moths are known to reside in forested areas, they have been showing up in places such as Raffles Place offices and Jalan Besar stadium, which are not in close proximity to any forested area.

It is also not known how big the giant moth population is.

Source: Warren Wu

4. Unsubstantiated observation - unusually high numbers of Singaporeans born between 1980 to 1984 who have Lepidopterophobia, or the fear of butterflies and moths. 

Probably an urban legend, but many Singaporeans who were born during this period report an irrational fear of butterflies and moths. Well it could be due to this 1988 SBC Channel 8 show called Mystery.

We'll let you relive your worst nightmare:

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