Why you’re seeing these loud buzzing insects in your garden

During the heatwave, I spread a layer of mulch over my backyard in preparation for fruit tree planting and by the next day found a number of dead, shiny green beetles on top of the mulch. 

These were easily recognizable as fig beetles, those loud buzzing insects, sounding like bumblebees, that visit the garden from spring until early fall, when they disappear. Upon researching their life cycle, I learned that female fig beetles die as soon as they lay their eggs, which happens annually between July and September. The eggs are buried six to eight inches deep and hatch into larvae about two weeks later. Larvae have six non-functioning legs and are known as “crawly backs” since they use the stiff hairs on their backs for locomotion. Between fall and late winter, the larvae will molt three times until pupation begins as the weather warms, but may not occur until midsummer. In any case, after two to three weeks in the pupal stage, adults emerge. 

Fig beetles are native to the Southwest. They were in California long before anyone had planted a fig or any other fruit tree in this part of the world. Originally, their diet consisted exclusively of cactus fruit, flower nectar, and sap from native trees, but today they are nourished primarily on homeowner fruit. They are especially attracted to figs, peaches, nectarines, and plums, and you may see a bevy of them clustered on a single fruit. In fact, a recommended practice for ridding your garden of fig beetles is to distribute overripe fruit throughout your garden as traps; when fig beetles settle on the fermenting fruit, you toss it into a bag for deposit in the trash. Of course, if you had a few chickens, you could feed the beetles to them. Fig beetles are primarily attracted to overripe fruit, but if birds first peck at a fruit, even if only partially ripe, this will invite fig beetles to dive bomb in for a snack. 

Fig beetles have a reputation for being clumsy with poor vision and, indeed, they have crashed into me while I was innocently preoccupied with gardening chores on several occasions. Rest assured, these insects — as well as their fat, imposing larvae — are completely harmless to us, even if they can render our fruit inedible. You will find fig beetle larvae in your compost pile or mulch where they perform a service by assisting in the decomposition process. Even so, if you wish to get rid of the larvae out of concern that they will become beetles that party on your fruit, expose them to the air and this will cause them to dry up and die or, alternatively, they will become a meal for passing birds.

Another creature that was recently concerning to me, more formidable possibly than a fig beetle, was a skunk or, for all I know, a family of them. I often wake up when it’s still dark and walk around my yard to see if any critters are about. Over the years, I have seen raccoons, opossums, and skunks. A number of years ago, skunks had even found a way into the crawl space under my house, but I succeeded in getting them out by putting screens over my crawl space openings during the night when they were out and about. 

But now I was completely mystified as to how skunks should be around since my crawl spaces are now closed and my yard is fenced. However, I had a conversation with my neighbor who had also seen skunks in his yard. He informed me that a skunk only needs a few inches under a gate or fence to squeeze through and he had witnessed this amazing capacity for contortion on several occasions. He reassured me that all I needed to do was to put large stones or bricks to close off any possible entry points and the skunks would not be able to get in. I did as he recommended, blocking even the smallest open spaces under my driveway gate and fence, and the problem was solved. 

Now the only uninvited guest is an opossum; it no doubt nests in a neighbor’s tree and rappels down from there. Interestingly enough, although my vegetables had all been harvested, skunk and opossum still came into my yard. The reason, no doubt, was grubs. Even before I laid my mulch I had seen spots where the soil had been dug up as nocturnal critters searched for those succulent treats. There are chemicals you can apply for grub control but I prefer to exclude the animals that dine on them.

If you are put off by the work associated with starting a vegetable garden, you shouldn’t be. The trend, these days, is to build a planter box — or order one ready-made — and then fill it with topsoil and compost. You don’t have to worry about softening up the dirt in your yard since you will be bringing in designer dirt of your own. The box you build can be as deep and as long as you wish but it should not be more than three feet wide. Planter boxes, or conventional vegetable or flower beds for that matter, will be difficult to maintain if they are wider than three feet since you will not be able to reach every plant comfortably due to interference from surrounding plants. If you have back problems and want to garden without bending over, that’s not a problem with planter boxes, which can be as tall as you want them to be. I have seen four-foot-tall planter boxes and must report that the people tending them were aglow with tales of how easy it was to garden at such an elevation. 

As far as soil is concerned, you can find a 50-50 mix, which means 50 percent topsoil and 50 percent compost wherever soil amendments are sold and delivered in bulk. Ideally, the top six inches, at least, of your planter box soil profile should consist of this mix. Do an internet search for “soil amendments” with your location to find a supplier of soil products in your area.

California native of the week: As bulb planting season is upon us, it is worth mentioning the Humboldt lily (Lilium humboldtii). This is a tiger lily, meaning it is orange with spots that are either black or, as in this case, dark crimson. Many lilies, including this one, are also referred to as Turk’s cap lilies due to their form. There are more than 50 species and subspecies of California native lilies, most of them orange, but they may also appear in yellow, red, maroon, pink, or white. Most of these lilies are endangered and, in our area, almost never encountered in the nursery trade, although their seeds may be found through internet vendors. 

I think a person could make a fortune finding a way to grow a mass of Humboldt lily bulbs; even seeds are hard to find. Unlike familiar flowering plants that grow from bulbs, most of which are not water-needy, the habitat of California lilies is a shady woodland environment with moist soil. Humboldt lilies – whose habitat includes the Santa Monica Mountains – are different as they are capable of surviving on an occasional soak during the summer months. After their seeds are planted, it will take three to five years for Humboldt lilies to bloom.

However, the wait is worth it when you see up to 30 flowers blooming on a single stem. They are three inches across and have the appearance of hot air balloons. Humboldt lilies are named after Alexander von Humboldt, the famous German plant explorer. Although von Humboldt met with Thomas Jefferson in the White House for botanical discussions, he never made it to this part of the American continent. Has anyone reading this ever grown a California native lily? If so, I would be delighted if you would share your experience with our readers and me by writing to joshua@perfectplants.com.