Is there a caravan of slugs heading toward your yard?

DEAR JOAN >> Fortunately, we have not had any ant invasions, and our rat invasion was taken care of when we had professionals set traps and block access points. The one rat that was seen outside after that moved on when we put pepper sauce on our bird seed.

However, when the recent rains came, we noticed slugs on the front porch and driveway. There were lots of them.

Most were rather small, but a few were more than an inch long. We have never seen them like this before. Is this one of those cyclical things? Do we need to be concerned for the safety of our plants, and, if so, what do we do? — Rich Cordes, Pleasant Hill

DEAR RICH >> It seems every time I turn around, there’s a new invasion to deal with. Maybe I should stop spinning so much.

The abundance of slugs is not exactly cyclical, but like with the rats and the ants, there are more of them at certain times of the year. The weather and our own actions can make a difference.

The slugs — and their brethren, the snails — are always with us, but the rain and mild winter temperatures can bring them out in larger numbers.

You’ll find plenty of slugs in the summer, but the heat and dry weather means they generally only come out at night or early morning, when the air is cooler and damper. On cloudy, cooler days, however, you’re more likely to see them out living their slug lives.

You might be surprised to learn there are at least a dozen types of slugs in the Bay Area — and many more throughout the state — including the reticulate tail-dropper, the hedgehog and the California banana slug. Your visitors were most likely the common garden slug, although to be fair, that’s what we tend to call all slugs unless they are fabulously colored or overly large.

If you look closely at a slug, you’ll see a cowl, or lump, on its back near the head. The size of the cowl is one of the things researchers look at when identifying the slug type. They also peek under the cowl, which covers the slug’s genitalia.

All land slugs are hermaphrodites, having both male and female genitalia, and a slug only needs another slug to reproduce. They reach maturity in about three months and, after mating, they lay up to 40 translucent eggs in protected areas, such as under leaves.

Slugs and snails create the greatest damage in our gardens, but part of it is our fault. To keep their numbers low, we should plant in sunny spots, avoid overwatering and keep leaf litter cleaned up. Ground cover also is a primary breeding ground for slugs and snails.

What we plant also can make a difference. Like most of us, snails prefer succulent foods and are especially fond of cabbage and strawberries. Plants such as lavender, rosemary, sage, geranium, hydrangea, California poppy, nasturtium and lantana are less appetizing.

To control slugs, you can always handpick them. Slug and snail baits that are made with iron phosphate are effective and do not endanger other animals. Avoid using baits with metaldehyde, which can poison cats and dogs. You also can use copper strips along your beds to keep them out.