They’re back.

When we arrived home on Saturday afternoon, clouds of multi-colored Asian ladybeetles were hanging around outside our front door. The change in the weather had brought them out. It had been a wonderfully warm afternoon, bright with sunshine after a couple of cooler and drearier days. Now there wasn’t going to be a way to get into our house without having to deal with them.

Saturday was actually only the beginning. Since then we’ve had to put up with hundreds of them crawling up the walls by both doors, while hundreds more cluster on the steps or on the windows. Thousands, it seems, fill the air, ready to fall into our hair or cling to our clothes.

Nasty, despicable bugs! What did we ever do to them that they bring us so much trouble?

No matter what techniques or strategies we use to thwart their progress, they never give up. They bite. They leave spots on the door and walls, little ones when they’re alive and big fat ones when they’ve been squished. And they smell really bad when you do squish them &045; we’ve used one of our vacuum cleaners to suck up so many of them it permanently spreads the stench of dead ladybug whenever and wherever we use it.

Where did they all come from? This is the question I have asked every fall since they started showing up. When I’m out gardening or walking the dog during the summer, I hardly see any ladybugs at all. There aren’t crowds of them on our tomato plants or in the flowerbeds. While we don’t spray for bugs in our yard, the fields around our house were sprayed for all kinds of pests. Since the thousands I’m seeing now weren’t in our yard back then, how did these ladybeetles survive? Something seems out of balance here!

The Asian ladybeetle infestation is a problem of our own making, of course. These beetles were imported from their home in Asia and released here in order to combat some other bug pest &045; despite their &uot;cute&uot; name, ladybeetles are voracious predators. Even though originally it was only a few thousand specimens, the &uot;new world&uot; has been good to them. They have thrived in the absence of their usual enemies and environmental stresses.

I wonder, too, if the way we carry out agricultural pest control is one source of our problem. When scientists examine the success of pesticides used in agriculture, they find that many of the poisons kill the &uot;good&uot; bugs along with the &uot;bad&uot; ones. Spray a field for weevils and we also kill the spiders and other predators as well as the bees and butterflies that pollinate the plants we’re trying to grow.

Most of the time we humans are only trying to kill destructive pests like weevils, or aphids, but in the process we usually end up killing the bugs that eat them, too. Sometimes, as in the case of DDT, the killing keeps moving up the food chain until it gets to the top predators: eagles, wolves and humans.

When we use pesticides over wide areas, a special kind of natural balance is destroyed. Whatever kind of creatures we’re talking about, it takes most predators much longer to rebuild their population after large numbers have been killed off than it does for the prey species to re-establish itself. It’ s one of the ways nature maintains its balance between predator and prey. Spraying poison around that kills everything only sustains a situation that leads to more spraying of poison, and the natural balance of the system rarely re-emerges. Sometimes we end up with a plague of prey, sometimes with one of predators.

Did spraying for aphids earlier this year help create an imbalance that led to a bumper crop of ladybeetles? Would not spraying those aphids have made a difference? Can we spray the fields for ladybeetles now without damaging the environment even more than we already have? I don’t know enough about biology to answer those questions. There are people with the necessary expertise, though, and I wish they would look into it.

Our current ladybeetle infestation may be a completely natural phenomenon; one we would never have been able to control. On the other hand, if it is a problem we’ve created for ourselves, then we should be able to do something to set things right again.

(David Rask Behling is a rural Albert Lea resident. His column appears Tuesdays.)