Q: A barrel cactus turned brown and imploded. The center caved in and became an orange slime. I found these white larvae inside about an inch in length. What can I do to prevent this from happening to my other barrel cacti?
A:Β The larvae are maggots, aka fly larvae. These insects are decomposers and attracted to the rotting plant rather than being the cause of the problem. The rot may have been caused by a wound that allowed a bacteria or fungi to invade. Overwatering is another potential cause. If you can describe your watering schedule, we might be able to rule that in or out. Typically, cacti should receive water every 10 to 14 days to a depth of 12 to 18 inches during the summer, every 21 to 28 days during the spring and fall, and none during the winter. Preventing this damage from happening to your other plants is not always possible because other animals may damage your cacti. What you can do is to care for them properly, which you may already be doing, and hope for the best.
Peter L. Warren is the urban horticulture agent for the Pima County Cooperative Extension and the University of Arizona. Questions and photos may be emailed to tucsongardensage@gmail.com
