Some weeks, it may seem like this blog is more about bugs than about plants. Isn’t gardening all about the plants? Well, it probably should be, but our gardens exist in the natural world, which is crowded with many kinds of life, including insects. Some of the insects are helper-insects, like pollinators and predators (“beneficials”). Other insects are destructive, eating our plants or spreading diseases across our landscapes (“pests”).
Some insects can be helpers as adults and pests in their larval stage. A lot of butterflies and moths are in this category. As adults, they pollinate flowers, helping plants to make fruits and seeds. As caterpillars (larval stage), they eat our plants. This dual life complicates a gardener’s decisions about how to manage caterpillars in the garden.
Which insects are “good” and which are “bad”? How can we know what to do when baby insects, like caterpillars, eat plants in our gardens?
For me, the decision often comes down to whether the insect specializes on one kind of plant, especially if I am not planning to eat that plant. A lot of the skipper butterfly larvae eat turfgrass. Bermudagrass is not my most favorite plant, so I am not troubled when caterpillars are munching on the lawn.
However, the decision about how to manage pest insects in the garden could one-day disappear. You may remember the report last year of a study in Germany that showed a 75% loss of flying insects within the past few decades.
The authors of the study note:
The widespread insect biomass decline is alarming, ever more so as all traps were placed in protected areas that are meant to preserve ecosystem functions and biodiversity. While the gradual decline of rare insect species has been known for quite some time (e.g. specialized butterflies [9, 66]), our results illustrate an ongoing and rapid decline in total amount of airborne insects active in space and time.Article appearing in PlosOne, 18 Oct. 2017
A recent article in the Washington Post, “‘Hyperalarming’ study shows massive insect loss,” tells about another long-term study in Puerto Rico that shows the same trend. We are losing insects of all kinds, and in great numbers. Why should we care? The article offers a reason:
Thirty-five percent of the world’s plant crops require pollination by bees, wasps and other animals. And arthropods are more than just pollinators. They’re the planet’s wee custodians, toiling away in unnoticed or avoided corners. They chew up rotting wood and eat carrion.Washington Post article by Ben Guarino, 15 Oct. 2018
To some gardeners, no longer having to worry about pest insects may sound like a dream come true. Sadly, the good and the bad go together. If we lose our pests, we also lose our helpers. This means we also lose a lot of good food and our “wee custodians”.
It may be possible for us to live on wind-pollinated crops, like wheat, corn, and beets, and on self-pollinated crops, like most of the beans. I don’t think we’d like that diet, though. In addition, being surrounded by rotting carcasses would make the situation extra-unpleasant.
While I don’t expect total losses of insects any time soon (or even in my lifetime), the thought of such a catastrophic loss of beauty and helpfulness is sobering.
What can we do to change the situation? Well, any action that supports insect life could help slow the decline. Try this:
- plant more wildflowers to support native pollinators,
- allow more diverse plantings in our yards, to provide more places to live for more kinds of insects, and
- refrain (as much as we can) from using pesticide products in ways that kill multiple kinds of insects instead of just the one pest that is “bugging” us.
One step that is both simple and difficult: plant clover in the lawn.