Bad bugs can fool you; they keep changing

This is not a good bug to find in your vegetable garden: It's a Leptoglossus zonatus , a leaffooted bug. (Photo: Debbie Arrington)

Just when you think you can tell a good bug from a bad bug, Mother Nature throws you a curve.

Some bugs transform into several different forms – called instars – before they fully mature. They keep molting and going through various stages of metamorphosis until they become complete (and much more recognizable) adults.

Right now in Sacramento gardens, multiple generations of leaffooted bugs are scrambling over our tomatoes. They’re not only different ages, but different species, and some of those bad babies mimic good bugs.

The leaffooted bug, a stink bug cousin, gets its nickname from the leaflike extensions on its back legs. The nymphs generally stick together for protection. The adults can fly and are much more mobile.

A fellow gardener at Fremont Community Garden found one on his tomatoes, and wondered if it might be an assassin bug, which is a predatory insect and considered a garden good guy.

Usually, the leaffooted bugs we see at Fremont, located in Midtown Sacramento, have little zigzag stripes and they’re pretty big – over an inch tall. That’s Leptoglossus zonatus .

A Leptoglossus occidentalis , a type of leaf- footed bug. (Photo courtesy Alan Moritz)

But it’s still a leaffooted bug, an immature Leptoglossus occidentalis . If you look closely, you can see the beginnings of those back “leaves.”

According to the UC Cooperative Extension pest notes, leaffooted bug populations tend to swell in late June and early July.

“Overwintering leaffooted bugs can lay over 200 eggs during a two-month period in the spring,” say the pest notes. “Nymphs emerge from the eggs about 1 week after being deposited, after which they develop into adults in 5 to 8 weeks.

"Adults are long-lived and can lay eggs over an extended period, so the population can consist of all life stages by late June. At this time, overwintering adults are still alive as the first generation of their offspring develop into adults.”

Throughout the summer, two to three generations of leaffooted bugs may be coexisting in the garden at the same time. And they’re all hungry. They go after tomatoes (in particular) but are a real pain on pomegranates, too, as well as a wide range of other fruits and vegetables.

The best way to combat them: Knock them off the plant into a pail or dishpan of water with 1 teaspoon dish soap (to break surface tension). They can’t swim and they’ll drown.

They tend to scramble sway from people, so slip the container under the tomatoes, then make motions from above or gently shake the vine’s trellis. The bugs will hop off the fruit – and right into the water. For pomegranates, gently shake the fruit over water; the baby bugs will fall out of the fruit’s blossom end.