Have you heard about the Bagrada bug? It is a relatively new garden pest here in Pinal County.
The Bagrada bug, Bagrada hilaris is sometimes known as the painted bug. Native to Africa, India and Pakistan, it was first spotted in California in June of 2008 and arrived in Yuma in September of 2009. It has since spread to other parts of Arizona including La Paz, Maricopa, Pima, and Pinal counties.
Feeding sites have been found on corn, cotton, potatoes and other crops, but plants related to cabbage seem to be favorite targets. Cabbage relatives include: kale, mustard, cabbage, arugula, broccoli, cauliflower, radishes and Brussels sprouts. Look for yellow spots, we call it stippling, along the margin or edges of the leaves. As feeding gets heavier, the stippled areas merge and the leaf can eventually wilt and die.
Another more serious symptom is “blind head,” a problem in heading species like broccoli and cauliflower. These vegetables develop a flowering head, which is the part that we eat. Bagrada bug feeding can keep the head from developing.
The Bagrada bug is a true bug, that means that it is classified in the order Hemiptera. Like all true bugs, it has a piercing-sucking mouthpart, six legs and a triangular-shaped shield on its back. Other true bugs include the lygus bug, the stink bug and the leaf-footed plant bug. All are major agricultural pests in Pinal County.
The insect piercing-sucking mouth part is most easily compared to our familiar soda straw. The straw is a tool to get liquid from a cup or can to our mouths. Likewise, the insect uses its mouth part to pierce the outer defenses of the plant and slurp up the nutritious plant juices. This is obviously not healthy for the plant because it is losing important nutrients and fluids to the invading insect. A heavy population of insects can drain a plant in short order.
The insect is about 1/4 inch long with a black body that is splotched with orange and white markings. Some of the markings are distinct, large spots. Those along the center of the back, however are stretched into long lines. The colors are distinctive, but resemble those of a harlequin bug, another distant relative. Be careful that you do not confuse the two. If you are into gardening, you may want to get a copy of a good color photograph and keep it handy so that you can compare what you have with the photo.
To download a photograph and get additional information, go to the University of Arizona Cooperative Extension website at http://cals.arizona.edu/pubs/insects/az1588.pdf and type in bagrada in the search line. You can print off the PDF version of the publication without charge. Another option is to go through your web browser and search for the name of the insect. There are many sites with good photographs.
While the Bagrada bug does have wings, it seems to prefer walking more than flying. Once the insect finds a good place to feed, it tends to settle down and stay a while. The life cycle of the insect begins with an egg laid by a female adult. She generally will lay the egg on the ground underneath the plant but sometimes she will select a site on the plant itself. Look for creamy-white, oval-shaped eggs with a band around it that make it look like a lid. The eggs change in color to orange as they mature.
As a true bug, it does not produce a caterpillar stage that looks completely different from the adult, like moths and butterflies. Instead, the newly hatched insect closely resembles the adult stage. The young are called nymphs. In the immature stages of growth, they lack wings and can only walk to move around. There are five juvenile stages that each insect must pass through before they become adults. These newly hatched nymphs are colored orange-red and get darker as they mature into the later juvenile stages.
If they show up in your garden, be ready for a blitz. They like to gather together in large clusters and as many as 2,000 nymphs of different stages have been seen feeding on a single cabbage plant. Talk about stress! No wonder affected plants go into shock. If we want healthy plants, we should never let a population get that big.
So, how do we do that? A good plan of action will include frequent monitoring of plants and a careful balance of cultural control methods including the use of a mixture of nonchemical and chemical control tools. Here are some specific guidelines recommended by entomologists down in the Yuma area where they have been battling the bug.
First, make sure that you check your plants regularly, at least weekly, to look for eggs on the leaves or soil. Allyssum is a known host for the Bagrada bug and that is a good place to start looking if you have some planted in your yard.
Second, hand pick the insects early in the season to help keep populations down. If you are squeamish, use gloves or a tool like a pocket comb or small paint brush to pick them up and drop them into a container where they can stay until you destroy them. They are relatively easy to find because they tend to group together.
Third, cultivate the soil around your plants with a hoe or other tool to break the crust of the soil and bury or destroy any eggs that might be lurking on the soil. At the same time, get rid of any crop debris and weeds that might be harboring the insects.
Fourth, use a soapy water solution to spray the insects, especially nymphs. Insecticidal soap sprays tend to clog the breathing holes of the insects and break down the soft, outer protective layers of the insect leading.
Fifth, use an insecticide containing a pyrethroid to clean up residual populations. I know that for some that this may not even be an option, and I suggest this as a last resort because no one really enjoys dousing something that they will eventually eat with pesticides. However, used correctly, these pesticides are safe to use. Just be sure that you follow label instructions when mixing, applying and waiting the proper interval before you pick and eat the produce. If populations explode on you and you cannot seem to get ahead of them this may be your best option.
If you end up with a heavy dose of the bug on your plants and can’t seem to get them under control, it will be important to cut your losses and get rid of the infested plants. Pull them up and toss them out. If you don’t, the adults will keep laying eggs until the end of the season and you will end up with an insect population waiting in the soil until you plant again. Not a pleasant thought.
The Bagrada bug is a new garden pest that could complicate our efforts for high quality, home grown vegetables. However, by carefully monitoring our gardens and treating for these pests in a timely manner, we should be able to prevent serious problems.
If you have questions, you can reach one of the master gardeners at the Cooperative Extension office, 820 E. Cottonwood Lane, Building C, in Casa Grande. The telephone is 520-836-5221, ext. 204.
Rick Gibson is an agricultural extension agent and the director of the Cooperative Extension in Pinal County. His email address is firstname.lastname@example.org.