From Hill County Ag and IPM:
Winter is here, and the multicolored Asian ladybeetles are making their presence known. They are an invasive insect in the US and several other countries, and are out-competing our native ladybug species, but they still provide excellent biological control and are considered in most agricultural and garden settings to be beneficial.
|Photo by Pat Porter|
|Photo by Pat Porter|
Identification Look for the 'M' shape on the carapace (back of the head). These beetles are aptly named; they can be any variety of colors from white to orange to deep red, and can have many different numbers of spots.
Rumors This picture is floating around the internet causing (understandable) alarm for pet owners. The dog pictured has multicolored Asian ladybeetles on the roof of it's mouth. Most likely the dog ate something with the beetles already on it, or slept with its mouth open and they found a nice warm place to overwinter.
|Multicolored Asian ladybeetles inside a dog's mouth. This is NOT dangerous!|
Rest assured that this DOES NOT HARM the dog in any way, other than give it bad breath! The beetles are not burrowing or biting, and they can be simply scraped off with a finger. They are not poisonous if accidentally ingested. This is very likely a rare happenstance, it is not beetle behavior to seek out animal mouths to rest in.
The Truth: Is it a Pest? These ladybugs can bite, but the bite is not harmful and won't break the skin. More importantly, they can emit a foul-smelling yellow liquid that can stain fabrics. It is this chemical defense that elevates them to 'pest' status in homes, as well as vineyards, where their presence (due to their overwintering in grape clusters) has been found to alter the taste of wines. You can read more about this phenomenon here.
In their native habitat these ladybugs spend the winter huddled together on cliff faces. Here in America, where they were introduced in 1916 to control aphid pests, we don't have cliffs, we have houses. Cue the invasion! Fortunately, they do not cause any damage to carpets, wood, or other household items except for the occasional stain.
What to Do If you've got ladybeetles where they don't belong, simply vacuum or sweep them up and toss outside or in the outdoor trash. Don't bother with chemical sprays or sticky traps, they aren't effective (traps) or necessary (pesticides) in this situation. Also, don't crush them or otherwise handle them, or you'll find out just how foul that liquid defense is.
To prevent them from bothering you in the future, seal up cracks and crevices in your homes with caulk or weather stripping.