We need to learn to value insects and other beneficials for the vital roles they play in keeping our gardens healthy. Learn to recognize the good guys because they are essential allies in keeping the bad guys in check. Work with them in creating a well-balanced vibrant garden.

Is a “good” insect always a “good” insect? To be precise and concise, the answer is “No.”

Is a “bad” insect always a “bad” insect? The answer to that question is also “No.”

Let me clarify. In the world of nature, an insect is neither good nor bad. Each one is considered to have an essential role in maintaining a balanced, healthy ecosystem. Maintaining a balance seems to be one of nature’s primary objective.

Introduce the human perspective and the whole picture changes. Since our goals are somewhat different, we typically define an insect as “good” or “bad” according to whether or not that insect assists us in meeting our goals.

Most of us have been taught to respect the praying mantis family as beneficial because it preys on a variety of garden pests. Actually, the praying mantis will eat anything that it can catch that doesn’t harm or eat it first. Its menu can and does include other beneficial insects. It even eats other members of its own family if given an opportunity! The praying mantis isn't  the only beneficial that be cannibalistic. Lacewing larvae will devour their siblings on occasion, and even our revered milkweed assassin bug (photographed by the Master Gardener Photography Team) can find itself on the business end of another milkweed assassin bug’s deadly beak (Figure 2).

Even the lady beetle family, most of whose members happen to prey on things humans classify as pests, has a few “bad” members. Consider the Mexican bean beetle. It can wreak havoc on the leaves of bean plants and, consequently, have an adverse effect on yields.

What about those insects most gardeners consider pests . . . the “Bad Bugs”? Avid butterfly gardeners are delighted to see larvae of the beautiful giant swallowtail butterfly on a Meyer lemon tree. In contrast, an avid citrus grower would probably scramble for his favorite pest control agent if he encountered the same larvae (known as orange dog caterpillars).

An assassin bug, usually a horticulturist’s best friend, is not likely to see a “Welcome . . . My Garden Is Your Garden” sign in a butterfly gardener's garden. Why? Because assassin bugs are effective predators of caterpillars and a butterfly gardener wants caterpillars to eat plants so everyone can enjoy the beauty of butterflies!

One last poignant perspective. Is a honey bee a "good" insect or a "bad" insect? The likely response is that the honey bee is a good insect because it provides honey and pollinates our plants. But if a honey bee stings you . . . then is it a good bug or is then a bad bug?

Whether or not an insect benefits or harms mankind is quite incidental to its main business, which is to ensure its own survival and that of its species. Truly, an insect’s “goodness” or “badness” is in the eye of its human beholder.

 

 

 

 

 

 

 

 

FIGURE 1. “I got Good Bugs and I have Bad Bugs.” Pictured
above are two milkweed assassin bugs (Zelus longipes)
dining on a fly. We would likely prefer to have
uncomplicated categories when it comes to what’s a
“Good Bug” and what’s a “Bad Bug.” In reality, an insect’s
“goodness” or “badness” is in the eye of its human beholder.

 

FIGURE 2. Milkweed assassin bugs are solitary insects.
On occasion, adults will prey on smaller-size immatures
(known as nymphs) when they are in very close proximity.
Although not very common, insect predators that are
general feeders are more likely to be cannibalistic
when the opportunity present itself.

 

FIGURE 3. If you are an avid citrus grower, orange dog
caterpillars are not likely to be on the welcome list for
insects. In contrast, some avid butterfly enthusiasts
grow citrus as a food source for these caterpillars
which are the larval stage of the colorful giant
swallowtail butterfly (Papilio cresphontes).

 

FIGURE 4. Spiders are excellent predators and general
feeders of flying insects. Honey bees are fair game
but spiders are not likely to have a significant
impact on overall honey bee populations.

This web site is maintained by Master Gardener Laura Bellmore, under the direction of William M. Johnson, Ph.D., County Extension Agent-Horticulture & Master Gardener Program Coordinator.

All digital photographs are the property of the Galveston County Master Gardener Association, Inc. (GCMGA) © 2002-2008 GCMGA - All Rights Reserved.