The Coastal Gardener:

During August, I often hear an approaching green fig beetle before I see it. Out in the garden, it sounds like a jumbo jet coming in for a landing.

These giant fig beetles are terrible navigators as they clumsily bump into almost anything that is in their way. Buzzing in circles and zig-zagging their way, they seem to be unable to distinguish a white wall from open sky.

I hear the buzz, then whack! as it smacks into the house — or me. Momentarily dazed as it wiggles on its backside; stunned but no worse off after its crash landing. In a few moments, it’s back on its feet, stumbling through the neighborhood in search of lunch, dinner or both.

For dining, this huge, metallic green beetle prefers all-you-can-eat fruit salad bars. Ripe peaches or nectarines from your backyard tree are a favorite, but almost any soft fruit will do, including figs, plums, apricots, grapes, berries and others.

Dawn, a regular reader, wrote me a note last week about these frightening-looking insects invading her garden.

“I live in Costa Mesa-Mesa Verde where many of the homes have mature fruit trees,” she wrote. “I myself have a peach tree along with a few grape vines. I have noticed these large green beetles in my yard in the past, but this year we have three times as many.

“I was lucky enough to save most of my peaches, but now the beetles are eating all my grapes. I am concerned, as I have read that these beetles can take over an entire fruit orchard, and may in the long run, affect our entire neighborhood.”

Dawn wants to know the best way to control these beetles without using major insecticides. Says Dawn, “Do we treat the lawn area for the eggs/grubs or do we try to eliminate the beetles as adults? We have tried some sprays, but they do not appear to be working. I really need your advice.”

Big, 1-inch-long fig beetles are a common sight throughout much of the southern U.S. during summer. Originally native to Arizona and New Mexico, they became noticeable in coastal Southern California during the 1960s.

Originally, cactus fruit were their native diet, but they now feed almost exclusively on garden and agricultural fruits.

As a child, I remember catching these beetles in midair, then tying a thread around one of their back legs and “flying” them around the backyard. It was great fun for me — probably not for the beetle.

Adult fig beetles can be intimidating, especially to non-gardeners. In spite of their size, fig beetles are completely harmless to humans.

Velvet green on top and metallic green on the bottom, almost every beetle you see has scratches on its back due to its many collisions with houses, vehicles, fences and even concrete driveways.

Control efforts, though difficult, are usually focused on the larvae, which are called grubs and feed on loose organic matter near the soil surface. These grubs may be as long as 2 inches, C-shaped and are a translucent cream color with a tan head. The larvae of fig beetles do not feed in lawns or on plant roots, as do some other beetle grubs.

Home compost piles are a favorite breeding ground for fig beetle larvae. The grubs are actually very beneficial in a compost pile, but are usually discouraged because of their menacing appearance and the fruit-eating habits of the adults.

Controlling fig beetles in a home garden can be very difficult. Chasing the adult beetles around the garden with insecticidal sprays is useless.

Start by inspecting neighborhood compost piles. If grubs are present, simply turning the piles more frequently and getting them to heat up will eliminate the grubs. Larvae are also common in manure piles at horse stables.

During summer, adult fig beetles emerge and begin searching for their dining options. They locate their meal not by sight, but from an odorless gas emitted by the ripening fruit. Damage is done as the adults scrape a hole in the fruits and feed on the flesh inside.

Ask Ron

Question: I want to begin worm composting, but someone told me that I can’t just use the earthworms from my garden.

Martha

Costa Mesa

Answer: That’s correct. Worm composting, also called vermicomposting, is becoming quite popular, even with apartment dwellers and non-gardeners. It can be done in a very small space (even indoors), is odorless and requires no heavy lifting or strenuous work. Almost all your kitchen scraps, which would otherwise go down the garbage disposal, can be composted by worms into a rich fertilizer and soil amendment. This includes scraps from produce, leftovers from meals, fruit remnants, etc. — almost anything that is organic, except for meats. The worms that are used for composting are red worms, not earthworms, and you can get them at most garden centers.

ASK RON your toughest gardening questions, and the expert nursery staff at Roger’s Gardens will come up with an answer. Please include your name, phone number and city, and limit queries to 30 words or fewer. E-mail [email protected], or write to Plant Talk at Roger’s Gardens, 2301 San Joaquin Hills Road, Corona del Mar, CA 92625.

RON VANDERHOFF is the Nursery Manager at Roger’s Gardens, Corona del Mar.