Harlequin Cabbage Bug: Another Form of Stink Bug
The Harlequin Cabbage Bug (Murgantia histrionica) is the common name of a bug that sucks the juices from Brassica plants and other garden plants. Popular Brassica plants include cabbage, broccoli, kale, cauliflower and kol rabi. These plants all belong to the mustard family.
If you have never seen a Harlequin Cabbage Bug, then simply plant a cabbage or another Brassica plant. Before long you will have many of the cute-little-devils. This is what science refers to as a true bug. A true bug goes through three stages of life. The life cycle of the Harlequin Bug begins as an egg. It hatches into a nymph and then develops into an adult (three life stages—egg, nymph, adult).
How Harlequin Bugs Survive Seasonal Changes
Here in Sacramento, California, we typically grow cabbage, broccoli and other plants from the Brassica family in the fall and winter. It is not uncommon to see these Harlequin Cabbage Bugs throughout the year. We are zone 8 and zone 9, and as such, it can get rather chilly if not downright cold here. These are hardy bugs that overwinter well. In warmer climates, they flourish year round and produce eggs and young on a regular basis. Here, we rarely see young Harlequin Cabbage Bugs (nymphs) during the later part of winter.
The life span of a Harlequin Bug is roughly between 50 and 80 days. This would suggest that the bug winters as an adult without much prospect of hibernation. This also means that for local gardens that little bit of warm weather we experience each February is prime spawning time for these bugs. Never mind that March here is typically wet. These bugs are well protected from torrential rains by the very plants they love to eat. Nothing speaks of early spring mornings like the beads of dew on the cabbage leaves. In fact, cabbage leaves and other Brassica foliage tend to repel water.
This is almost the beginning of August and the Harlequin bugs are rampant, despite the fact that we have few Brassica plants growing in the garden. They seem to prefer the waxy leaves of the struggling broccoli plants. They will investigate and sometimes enjoy a meal from chard, but for the most part, they seem to stick to plants from the cabbage or mustard family.
The Damage From These Striking Pests
As striking as these bugs are, they are truly pests. They are capable of ruining an entire crop of cabbage or broccoli, etc. by simply sucking the sap from the plants. Plants are much like people. When we are not feeling well, our immune system drops and we fail the thrive. With crops, it is more likely that the plant may simply wither and die.
The eggs of the Harlequin bug look like a double roll of sushi. They are almost laid in perfect rows and usually up to 12 eggs. If you spot Harlequin bugs in your garden, the eggs are easy to find. Simply look on the underside of the leaves of the plant on which you found the bugs. There you will more than likely find the eggs. You can remove the eggs by gently scraping them off the leaf. It is just as simple to remove the portion of leaf they are on as well. Depending on temperature variations the eggs can hatch in as little as 3–4 days or they may take up to 29–33 days to hatch.
Nymphs typically take four weeks (and sometimes as long as nine weeks) to mature before mating and laying eggs. When I first noticed these bugs in the garden, I thought that we had an odd species of ladybug. These were simply nymphs. They are about the size of a full grown ladybug, but their coloration is quite striking—a very distinct coloration of red and black with four very uniform black squares on their back. The nymphs molt up to five times before they become adults and each molting morphs the color and pattern of the nymph into a closer and closer duplicate of the adult patterns. I personally find these bugs to be quite beautiful. But I do not delude myself into accepting them for more than the pests that they are. Adults are about 1/2 to 3/4 of an inch long.
How to Control Harlequin Bugs Without Chemicals
There is a chemical somewhere that will kill anything, but that is not the goal of organic gardening. For smaller gardens, it is fairly simple to hand-pick the bugs and destroy them. This includes hunting for their eggs. The eggs are very easy to spot as they are laid right out in the open. In larger gardens, it may be an on-going process to hand-pick the bugs and eggs. Some farmers have planted small gardens that are designed to attract the bugs and then when the infestation is at its peak the garden is burned. That is a little extreme for me, plus the fire department would be there in a heartbeat.
I would like to express that while I encourage organic methods of pest control, commercial Brassica farms could be entirely wiped out without the use of chemicals to control these pests. This is important, not because I am endorsing pesticides, but because I wish to point out that, in grocery stores, organic food is usually higher in price, than non-organic food. That price reflects that work that it takes to grow presentable vegetables under organic conditions.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2011 David Stillwell