Insects are a fascinating group of animals.

Many scientists estimate that there are more than 10 million different species in the world. Fortunately, most are either harmless or beneficial to humans. They help recycle and break down organic matter, pollinate the plants we depend on for survival, provide us with medicines and silk, eat harmful insects and pathogens, and much, much more.

Despite the fact that so many insects are beneficial, there are still many that cause problems by spreading human diseases, eating crops and more. Right now, there are several different types that are causing area gardeners some hardships.

THE ROSE CHAFER
One of these insects, the rose chafer, has just started to emerge over the past few days. The adult rose chafer is a tan, slender beetle with a reddish head and long, spiny, reddish legs whose wings do not quite cover its abdomen.

The rose chafer emerges around this time every year and feeds upon a variety of hosts. These beetles seem to prefer the flowers of roses and peonies, new grapes and grape leaves. They will also damage apple, cherry, dahlia, elm, foxglove, geranium, hollyhock, hydrangea, pear, poppy, Virginia creeper and wisteria. Luckily, the adults only live for about four weeks.

While there are chemicals registered in the state of New York that can be used on the rose chafer, the species, like most beetles, is fairly resistant to pesticides. If you have a prized shrub or flower you wish to save from a rose chafer infestation, you can try covering it with row cover or cheesecloth to prevent the beetles from coming in contact with the plant. Just make sure you get the plant covered before it is covered with beetles. You don't want to trap them in your barrier.

You can also hold a soapy jar of water under the beetles and gently tap the plant's stem. When disturbed, the beetles have a tendency to drop and will fall into the water. After a few hours, they will drown.

THE APHID
A non-beetle insect that seems to be very prevalent this season is the aphid, which is no surprise. One aphid can produce 50 babies in one week, which in turn can reach maturity and start producing babies within seven days as well. These soft-bodied insects are their most prolific when the temperatures range between 65 and 80 degrees F.

Aphids are small insects with long, slender mouth parts that they use to pierce stems, leaves and other tender plant parts and suck out plant fluids. The majority do not have wings. Aphids can be green, black, yellow, brown or red. Their color depends on the species of aphid and the type of host plant.

Almost every plant has one or more aphid species that occasionally feeds on it. And most plants can tolerate a low population of aphids. Because of the insect's prolific reproduction ability and the fact that it is most commonly found on the bottom of the leaf where we don't see them, aphid populations can get high.

When that happens, you start to see deformed leaves and stunted growth. You may also see a black mold that grows on the aphid's sweet, sticky excrement. This is called sooty mold and is more a nuisance than anything else.

Besides growing mold, the aphid's excrement, called honeydew, is often eaten by ants. To help ensure a steady supply of food, these ants actually farm the aphids, protecting them from predators, moving them into their tunnels during the winter and also from plant to plant.

To reduce aphid populations, you can rely on predatory insects such as ladybugs. You can use a registered insecticide, including less toxic kinds such as insecticidal soap and neem oil, or you can blast them off your plants with a strong stream of water.

While these and other garden pests can cause us additional work and stress, it is always important to try to keep things in perspective. Remember that the number of insects that are garden pests is much smaller than the number that helps us out in one way or another.

Anne Lenox Barlow is the horticulture educator with Cornell Cooperative Extension in Clinton County. Office phone numbers: Clinton County 561-7450, Essex County 962-4810, Franklin County 483-7403. E-mail questions to: askMG@cornell.edu.