Q: Our yard backs up to the desert and every late summer for the past few years leafcutter ants raid our yard at night, stripping leaves off our banksiae rose and lantana. The have recently begun to attack a mature desert willow and it’s now almost bare. At one point the anthill was in our back yard and I used insecticide on the pile so that now they’ve moved into the desert. But they climb the fence with ease even while carrying leaves. I don’t want to spread poison in the desert but am worried our tree will not survive. (The lantanas and banksiae are hardy and always come right back). Do you have suggestions to keep the ants out?
A: Leafcutter ants are difficult to manage but one thing that slows them down is making the area less hospitable. A product called tanglefoot is a sticky substance you can spread on the base of the plants you are trying to protect and in your case maybe the wall they climb. Also diatomaceous earth is something you can spread on the ground surrounding the plants. The diatomaceous earth is abrasive and can injure the ants and the sticky stuff does just what you might think. They get stuck and can’t move much like Roach Motels that let insects check but not check out.
People are also reading…
Q: I am new to the area but have done extensive gardens and compost. Since I have scaled down my garden to a small area I invested in a compost tub. Adding to my kitchen and yard scraps, I put leaf litter from under a large Texas Ranger. Low and behold I found these 1-inch segmented worms, which are not the common earthworm. I looked it up on the Internet and they appear to be Black Soldier fly larvae or “Hermetia illucens.”
It stated they are very good for composting flesh, very quickly. My question is: they are in my compost bin and I don’t perceive they are harmful and will break down the plant matter, because I have not added any flesh, bones or oils to the bin, but if I add them to a planting bed along with my compost, will they eat young shoots or roots?
I have not seen any earthworms that I am familiar with; do they not survive in this soil/climate? Do I need to introduce them? If so, where would be a good place to get some? I love the feel of a good rich soil with sand for good drainage.
A: The soldier fly larvae feed on decaying organic matter including compost so they are naturally found in compost and do no harm to the compost or the gardens it is spread into. Overall they are a beneficial species and should be welcomed rather than feared.
Earthworms are great in the cooler months but they can’t take the heat in the summer of the desert. Some people keep their earthworms in a bin indoors during the hottest months or all year round. Kept properly, they don’t smell bad and you can use their compost as needed in your garden. If you decide to leave them outdoors, you will need to provide shade and some cooling effect to allow them to survive.
Q: I have a Mexican honeysuckle that I planted last April. It has been doing fine up until now. The leaves in the center of the plant are turning yellow. I fertilized the plant when I planted it and it has been on my drip irrigation system. I don’t see any insect problem. Any idea why the leaves are turning yellow?
A: Several things including overwatering, underwatering, nutrient deficiencies, and viruses can cause yellowing leaves. From the photo you sent, I see the newer growth looks much better than the older growth. I suspect the recent rains may be attributed to the improved health of the plant and I recommend you adjust your watering schedule to once every 14 to 21 days for the spring, summer, and fall, making sure the water reaches a depth of 24 inches each time.
Peter L. Warren is the urban horticulture agent for the Pima County Cooperative Extension and the University of Arizona. Questions may be emailed to plwarren@cals.arizona.edu
