Good Bug Bad - Orchid Board

BikerDoc5968 · #1 01-23-2009, 10:56 AM

I know this "looks like" a ladybug but is it a ladybug or just "a-wanna'be"? And if he/she is crawling around in the GH, could it be good or bad? Every winter these guys come into my home...we're talking snow, wind and sub-zero weather and they are everywhere!!!!!!

ronaldhanko · #2 01-23-2009, 11:10 AM

I don't think these are ladybugs, but an Asian ladybeetle (Japanese ladybug) - I don't know that they'll harm orchids, but they invade homes (sometimes in large numbers), they bite, they stink when you crush them, and they cause an allergic reaction in some people.

camille1585 · #3 01-23-2009, 11:16 AM

I recognize it, from my biocontrol course last week. It is a ladybug, Harmonia axyridis. It's recognized by it's 19 spots and the M shaped black mark on it's thorax,redish/brown legs, and the fact that it likes to overwinter in warm places. It is an asian species, introduced in Europe and the USA to kill aphids.
But while it is a good bug, the big problem with it is that it's population (at least in Europe) is growing rapidly, at the expense of the native ladybugs. This asian one actually feeds on the native ladybugs. I don't know if this is the case in north america, but I think it is safe to assume yes.

BikerDoc5968 · #4 01-23-2009, 12:29 PM

Trust me when I tell you that these little critters do absolutely INVADE the home in the winter! About3 or 4years ago. I was killing these guys at a rate of 10 to 12 a day..... 2 years ago I resided the house and this has decreased the population... maybe I sealed the exterior better and they have no place to go!!!??? Thanks to both of you.... Camille, looks like you have been studying very hard and it has paid off..... good for you! This is one link I found that tells about this lady beetle: Harmonia axyridis

ronaldhanko · #5 01-23-2009, 12:43 PM

A few years ago I was helping my son replace a shingled roof and the underlying plywood. When we tore the roof off the whole space between the rafters (joists) was full of these beetles.

Ethan · #6 01-23-2009, 01:22 PM

Hi, Doc -

We get these guys in our house every fall. Last fall I put some in the greenhouse thinking they would eat some bad bugs. For some reason they never lived in the greenhouse - too humid, maybe, I dunno.

Your post makes me laugh, though...I've been having a big aphid problem in my greenhouse for a couple months now (they came in with one of my plants this fall). What I wouldn't do to have some of your beetles to help me get rid of them!!!

greenbean · #7 01-23-2009, 05:39 PM

Quote:

Originally Posted by camille1585

I recognize it, from my biocontrol course last week. It is a ladybug, Harmonia axyridis. It's recognized by it's 19 spots and the M shaped black mark on it's thorax,redish/brown legs, and the fact that it likes to overwinter in warm places. It is an asian species, introduced in Europe and the USA to kill aphids.
But while it is a good bug, the big problem with it is that it's population (at least in Europe) is growing rapidly, at the expense of the native ladybugs. This asian one actually feeds on the native ladybugs. I don't know if this is the case in north america, but I think it is safe to assume yes.

Yep, definitely an Asian ladybug. Interesting point you bring up Camille. I did a search after reading this and there are no negative reports about Asian ladybugs in the U.S. I found one experiment that found that the Asian species out-competes the native ladybugs because they are more active at colder temperatures. Unfortunately, the experiment only mentioned the positive aspects of this detail. For farmers looking for biological pest control, it makes sense that a ladybug that continues eating aphids at lower temperatures is a good thing. But the study did not explore the ecological impact of a non-native species potentially displacing the native species.

But hey, I'm sure we Americans will start thinking about that and catch on right after it's too late to fix anything.

Ethan · #8 01-23-2009, 06:01 PM

Evan, you hit the nail on the head!! LOL

Maybe they don't have an ecological impact, I don't know, but I do know this:

They were supposedly introduced into Canada to control the aphid population and quickly moved south. In their native habitat (China, I think) they live/flock/swarm to the sides of large rocky cliffs. About 6 years ago when they first appeared in the midwest, I can remember seeing millions of them swarming around a couple 20 story buildings (resembling cliffs) one warm fall day.

Also, they do bite some people, but not others for some reason (not me, thank goodness) and I guess it doesn't feel too good.

Ecologicly, they could become a problem as it's my understanding they have no natural predators in the US (they taste bad to birds and other animals that would eat them). So, yeah, way to go America...worry about it when it becomes a problem.

LOL