Cabbage Butterfly not very welcome in gardens

The Cabbage Butterfly, a common little insect, is one of a small family known scientifically as the Pieridae.
There are three groups: the Whites, the Sulphurs, and the Orange-tips.
The names give you a pretty good idea of their colours. All of them are quite small, about two inches or so across the wings.
The main wings often have black marks at the tips, black dots or splotches, and some have black edges.
The Cabbage Butterfly is the most common one of all. It is white with black tips on its forewings, and one black spot on each forewing, too.
The female may or may not have black spots, depending on the season.
The larva of this butterfly is called the Imported Cabbageworm because it was not here in North America until about 1870, when it arrived from Europe by accident.
Now it has spread across the U.S. and the southern parts of Canada. This caterpillar is a real pest in certain parts of your garden, and for sure in those big market gardens.
The “worm” is about an inch long, green with a yellowish back, and covered with fine hair. The damage it causes is by eating the leaves—big, ragged holes are its trademark.
It also leaves droppings among the leaves, which doesn’t make your cabbage very palatable.
It will eat its way right into the main, solid part of the cabbage. It also eats other plants of the cabbage family, including cauliflower, kale, broccoli, and Brussels sprouts, as well as turnips, radishes, and some of the common weeds.
Here in the north, the Cabbage Butterfly usually will have three generations each summer. It winters over in the ground as a pupa.
One of the controls is to clean all of the cabbage leftovers out of your garden as soon as the crop is done. Then you should till the soil well and deeply.
There are other controls over this garden pest, too. Some of the natural ones are ladybugs (they eat the eggs).
Some of the parasitic wasps prey on them—even your friendly “yellow-jacket” at times. And some birds will eat them, too, although they tend to make some of the birds, including chickens, sick.
There are many insecticides which work very well on this little green caterpillar. If you don’t like chemical sprays, the bacteriological one Bt (Bacillus thuringis) works very well, too.
And here’s one which I never heard of until recently: use the legs of old pantyhose or old nylon stockings. Just put one over each cabbage head in your garden.
The mesh is too small for the butterfly to lay its eggs yet, of course, it lets in light, air, and moisture all the time.
As my Scots mother would say, “You can learn something new every single day.”
Here in North America, we have a whole host of imports—plant and animal, accidental and deliberate.
Most of them, like this one, are species which we would gladly do without. Too late now!