There's a new bug in town, and it's a bad one. The Bagrada bug, a.k.a. harlequin or painted bug, is an alien invasive insect that is spreading like wildfire throughout Southern California. It's a rather pretty creature with a black, shield-shaped body boldly marked with orange and white.
The Latin name for this bug is Bagrada hilaris, but there is nothing hilarious about them. It has quickly developed into a major crop pest.
These little stinkers were first spotted in Los Angeles County in June 2008. They have since spread throughout Southern California and into Southern Arizona.
Native to Africa, India and Pakistan, the Bagrada bug is also found in Southeast Asia and Southern Europe. Their recent arrival to the U.S. is already causing havoc in home and community gardens, as well as on organic farms. Population densities build quickly, and the infestation can decimate crops in the brassica family. This includes broccoli, Brussels sprouts, cabbage, cauliflower, kale, turnips, radishes and mustard greens.
Adults and nymphs insert their needle-like mouthparts into plants and suck out the juices. They leave behind white or wilted spots where they have been feeding.
Bagrada bugs are members of the stinkbug family and taste nasty to birds. If a bird eats one, it will immediately spit it back out. That means that Begradas have no predators here and are reproducing astronomically.
Other species of harlequin bugs lay their eggs on plants, where they can be preyed upon by wasps. Not Bagrada bugs. They lay their eggs in the soil. When those eggs hatch out, the nymphs attack the nearby plants in such huge numbers that picking them off by hand isn't feasible.
Vic and I have noticed these pests in our garden this summer, both at home and at the Huntington Beach Community Garden. They decimated my kale and my tatsoi (an Asian version of mustard greens). They seem to do nothing but destroy plants and make more little Bagrada bugs. At this time of year, the adults go in and out of cracks in the soil, and the females are busy laying their eggs below ground.
Because the time to plant winter brassica crops is nearly upon us, I thought it would be a good time to mention this emerging new pest. I wish I had an easy solution to offer, but I don't. Apparently, most organic remedies are not strong enough to combat Bagrada bugs. The popular organic insecticide called neem oil doesn't faze them. Row covers (lightweight netting that you drape over crop plants) will keep out flying insects, but since these Begrada bugs lay their eggs in the soil, they come up from below, so row covers won't help much, either.
Commercial non-organic farmers have had success with standard chemical pesticides like carbamate and the pyrethroids. I have read that the neonicotinoids also work, but these pesticides are thought by many to be responsible for the colony collapse disorder that is killing off honeybees, so organic gardeners are trying to avoid them.
In searching cyberspace for a way to combat this scourge, I didn't find much. Some people suggested vacuuming the bugs off the plants. I just can't see myself doing that. Heck, I don't even vacuum indoors. I sure as heck am not going to start vacuuming outdoors. I think if Vic saw me take a DustBuster to the Brussels sprouts, he would have me committed.
One method that sounded promising was solar sterilization of the soil to eliminate the eggs, followed by the use of row covers to keep off new insects. I used solar sterilization at Shipley Nature Center back in 2004 to kill off weed seeds. It is horribly expensive to do on a large scale, but feasible in the home garden.
After the crops are harvested, wet the soil thoroughly. Cover the soil with black plastic and stake it down with landscape staples. The sun heats the soil under the plastic to temperatures of 160 degrees, which should kill the Bagrada bug eggs. Leave the plastic on for two to three weeks, then remove it. Plant brassica crops and cover the rows with row covers made of landscape fabric. You can order row cover fabric and supports from Gardener's Supply Company online at http://www.gardeners.com.
Once again, we see how an invasive non-native species can be spread around the world by the activities of humans. This one was probably imported on some produce that came into Los Angeles. And when a species arrives in new territory, it often has no enemies and can spread willy-nilly. It may be some time before a good solution to this problem is found.
VIC LEIPZIG and LOU MURRAY are Huntington Beach residents and environmentalists. They can be reached at Lmurrayphd@aol.com.