From Seed to Seed:
Plant Science for K-8 Educators

Insect Troublemakers. Now that we have virtually deified insects, it is time to spend a few minutes with some of the ones that could give student gardeners a headache.

Most troubles occur with insects that are herbivorous-those that eat plant material. All plants and all plant parts, it seems, are subject to attack by one kind of insect or another. Take note of any nibbled leaves, flowers, or stems in your schoolyard garden. Engage your students by asking, Who do you think is responsible for this damage? Who benefited from this relationship-the insect, the plant, or both? Can you find the culprit? We say culprit because in most cases, the relationship is clearly parasitic-the insects live at the expense of the plant. One look at a broccoli plant skeletonized by cabbage loopers and you know the plant didn't derive much benefit!

Most insects go through four stages of growth: egg, larva, pupa, and adult. An insect's relationship to plants usually varies depending on its life stage. For example, many butterfly and moth larvae (caterpillars) are ravenous herbivores, and can quickly destroy entire plants. However, the adults are usually harmless, and sip only nectar.

As we said before, it is always a good idea for you and your students to identify any suspect insects before indiscriminately destroying them. You may discover that you've got a rare species of butterfly inhabiting your schoolyard garden!

Although we've just touched upon the complex nature of plant-insect relationships, it's time to move on and look at some plant-plant relationships.