An invasive species that's easily mistaken for the harmless ladybug is swarming into US homes by the thousands and may even attack the people inside.

State and federal officials have warned that the Asian lady beetle has become a potentially dangerous menace that bites people and damages property during the fall and winter months.

The insects also form 'death spiral' swarms which fly around the lights inside US homes, gathering in the walls in immense clusters of up to 15,000 or 20,000 bugs.

State researchers in Mississippi recently sounded the alarm that these insects would soon be trying to sneak back into homes by squeezing under window sills, looking for places to survive the winter.

However, the problem extends far beyond Mississippi, with Asian lady beetles being found in nearly every state in the US.

Not only do they have a pinching bite if they land on a person, but the ladybug impostors emit a defensive yellow fluid that has a foul odor, irritates human skin, and can stain fabrics.

The PennState Extension warned: 'It is not uncommon for tens of thousands of beetles to congregate in attics, ceilings and wall voids, and due to the warmth of the walls, will move around inside these voids and exit into the living areas of the home.'

The government-funded science advisors at Penn State added that the smelly yellow liquid could also trigger allergic reactions and sinus problems if the goo gets on someone's skin.

Although the Asian lady beetle (Harmonia axyridis) was deemed an invasive species by the US Department of Agriculture (USDA) in the 2000s, the bugs were not carried here by accident or sent here by another nation to cause harm.

The US intentionally brought the beetles here over a century ago from countries including China, Russia, and Japan to fight native pests that were killing crops and plants.

Decades later, the USDA released thousands of the pest-eating lady beetles in places such as California, Georgia, and Pennsylvania, using them as a 'biological control tool' in the 1970s and 1980s.

However, their numbers quickly grew out of control, and by 1988, agriculture officials found the first confirmed lady beetle colonies living in Louisiana.

The Mississippi State University Extension explained: 'During most of the year they are considered 'good bugs,' but as cold weather approaches, they start looking for a place to spend the winter, and this is when they can become real pests.'

Researchers from the University of Florida added that without the local predators, which eat lady beetles in Asia, their populations have exploded to the point where the pests are now endangering native ladybug species in the US.

Asian lady beetles are slightly bigger than normal ladybugs, and scientists have suspected that the invasive bugs are eating the eggs and larvae of US ladybugs in what they call acts of cannibalism.

US officials have grown increasingly concerned about the Asian lady beetle because as their population increases, native species die out, forcing farmers to rely more on pesticides that can pollute local water supplies.

If the Asian beetles do start to gather in your home, retired MSU entomology specialist Black Layton warned against using insecticides to kill the creatures as these chemical sprays could end up lingering in your house without clearing the invasion.

'The best advice I can give you once they get inside is to use a broom and a dustpan, or better yet, maybe a vacuum and just vacuum them up and get them outside,' Layton said in a Facebook video.

As for how you can tell the normal ladybugs from the foul-smelling, biting variety, Asian lady beetles are often orange instead of red.

They also have fewer spots than the traditional seven you can count on the back of a deep red-colored US ladybug. Moreover, the Asian lady beetle has a distinct black 'M' or 'W'-shaped mark on its head.

However, the biggest distinction is how the bugs interact with people. The slightly smaller US ladybug Americans are used to seeing in spring and summer does not bite at all.

They will crawl around on someone's hand if picked up, but will never attack or release any type of defensive liquids.