Exotic Insects

Walking Stick (Carausius morosus)
click to view large

We were surprised this morning to find this character crawling on the kitchen wall.

A quick check using the Internet, and we were pretty sure that it's a non-native species -- and one that could be a big problem: a Walking Stick. After reading this article, and this one, we decided we couldn't let this bug back out into the garden.

Some people think all bugs are bad, and should be crushed, poisoned, or swatted. Some people think that all bugs are good, and should be left alone to do what they want. If you've been to Archie's Garden or read the articles here, you know that we love bugs here -- but that still doesn't mean that we think all bugs should be treated the same way.

The walking stick insect is native to southern India, a place almost exactly half-way around the world from Archie's Garden. Where it comes from, it's part of a complicated balance. The walking stick insects eat the plants that grow there, but there are birds, spiders, rodents, and reptiles there that survive by eating walking stick insects. Because of these predators, the population of walking stick insects stays in balance.

Here in Southern California, there are plants that the walking stick insects like to eat. They like roses, berry vines, and ivy, but they can eat lots of other plants. But unlike in India, there aren't many birds, spiders, rodents, or reptiles in California that eat walking stick insects. This means that there is nothing to control their population. If we don't control them, pretty soon there will be walking stick insects everywhere.

This kind of creature -- one that is not native, and that has few natural predators -- is called an "invasive species" if it is too successful in its new home. Because they can do a lot of damage, people worry about invasive species.

What should you do if you find an insect (or plant or animal) that you think might be invasive? The first thing you should do is visit the web site of your state or county's Agriculture Department. For California, the Department of Food and Agriculture has a web page to help.