Thread-waisted wasps lead tough, solitary existence

Don’t panic, this column is not about cockroaches, although now that I think about it, they’d make an interesting topic …

But for the moment, they’re an example of how some insects can survive being yanked out of their natural niche for an alien environment. Just think of all the cockroaches that illegally entered the country while hiding in banana boxes, then thrived and multiplied.

Other insects don’t do well at all when removed from their comfort zone. Indoor spiders, for instance, are in deep trouble if tossed outside. And the two dead thread-waisted wasps on the window sill this week, the first ones I’ve seen in the house, fared poorly on a human stage.

Had a cockroach wandered in, its survival odds would have been high, no matter how clean the house might be. And since this particular wasp digs burrows, the next generation would never have been born unless she resorted to the soil of a potted plant.

Nectar provides a thread-waisted wasp with some energy, but she’s primarily a carnivore and caterpillar hunter, at least the species usually seen here. Neither nectar nor caterpillars were available in the house.

I say she because the stinger evolved from the ovipositor of females. No ovipositor, no sting. No sting, no injection of paralyzing toxin into the prey.

The thread-waisted (what a great description) wasp in this area prefers caterpillars, although some thread-waisted species prefer other prey.

Paralyzing the caterpillar is the easy part of the day. She has to drag it back to her burrow. This is no small feat. I’ve seen photographs of the journey and the caterpillars are about as long as she is (a tad more than inch), and much bulkier. She has to straddle it and using her mouth parts, bite into it and off she goes.

Entomologists have discovered that the thread-waisted wasp uses landmarks such as twigs and rocks to find her way back home. She had closed the burrow entrance before she left for the hunt, so she has to open it by removing soil particles.

Once the caterpillar is set in the burrow, she lays an egg on it, leaves and covers the nest again to protect against a number of tiny predators who would eat her baby. When the egg hatches, it’s breakfast in bed for the grub, who, as entomologist John Acorn once described it, devours the “zombie caterpillar.”

The thread-waisted wasp is most likely to be found in warm, sunny, open areas because it’s pretty tough to burrow into tall grass and then drag the prey through the obstacle course back home.

Because the thread-waisted wasps are solitary beings, there are fewer of them in any given area, thus you’re less likely to be stung by one.

On the bookshelf: “Best Hikes with Kids: Western Washington &the Cascades” ($19, Mountaineers Books) is an update version and combination of the two-volume “Best Hikes with Children.” Joan Burton’s advice is hard to beat, and there are several tweaks that make “Kids” more user-friendly.

The 480-page 183-hike book is squatter than usual and fits easily inside the glove compartment for spur-of-the-moment outings. Sections close to home include the Mountain Loop Highway and Stevens Pass.

Banff and Yoho national parks are some of the most spectacularly beautiful pieces of real-estate in North America. If you’d like to explore the geology behind the beauty, geologist Chris Yorath’s “How Old is that Mountain” ($25, CQHarbour) opens up the world of mountains and the forces that shaped the parks.

Columnist Sharon Wootton can be reached at 360-468-3964 or www.songandword.com.