Insects in your lawn and garden can be friend or foe. If you think you might have a problem with the smallest residents on your property, you might want to find and identify just what might be there. Beetles and other flying insects might make themselves known by visiting porch lights in the evening hours, but the best way to find out if you really have an insect problem is to perform a drench test, which will allow you to see just how many insects are making themselves at home in your lawn. Keep in mind that all lawns have some bugs, and the number you find with this test just might surprise you.
There is an acceptable threshold for many insects, even those that are considered pests. For instance, with the armyworms or cutworms, you want to find no more than five per square foot tested, but with cinch bugs or fiery skippers, 15 per square inch is the threshold. For more information on the thresholds for the insects that you might find I suggest checking the University of California Statewide Integrated Pest Management Program webpage or your local Cooperative Extension Service Office for more detailed or localized information.
The drench test involves just what you might expect from the name, drenching a specific area to draw insects up out of the ground so you can identify and count them. Knowing what you are dealing with can help you diagnose what lawn issues you might have. If lawn symptoms had you convinced that you had an issue with a specific pest, but they are not in residence you can move on to other possible problems, which would likely call for different treatments. It will help you either relax and stop worrying about a problem that is not there, or help you understand the exact nature and extent of your insect problems so you can take the necessary steps to solve the issue.
You will need:
Tape measure
Watering can
Measuring spoons
Jars
String
Landscape spikes or stakes
Dishwashing liquid
Water
Instructions:
1. Mow your lawn, or at least the testy area. Insects, particularly the smaller ones, can be hard to spot even in short grass. Therefore, it is best you give yourself the best chance of finding the insects by doing so in an area that has both healthy grass and some of a damaged spot that might have brought on your need to test for insect pests.
2. Measure and mark off a square foot section of your mowed lawn. Drive four stakes into the ground, marking the four corners.
3. Wrap the string around the four stakes securely in order to mark off the test area.
4. Fill your watering can with one gallon of water.
5. Add two to four tablespoons of dishwashing liquid to the watering can.
6. Drench the test area evenly with the soap mixture. The soapy water will bring most insects to the surface so that you can see them.
7. Collect the insects that you find by placing them in the jars. Separate the insects by type, keeping each type of insect in its own jar.
8. Count the type of each insect so that you can check the counts against the threshold limits. I suggest recording your counts in a notebook, or on the jars themselves, to allow you the most accuracy and ability to recall the correct counts. I am notorious for bad number recall, so I always write down anything I need to remember, particularly if I need to identify or further research something.
9. If you run across any insects that you do not already know, I suggest consulting your local Cooperative Extension Service Office for detailed information or looking at Bug Guide http://bugguide.net/node/view/15740 to identify the creatures.
You cannot decide on a course of action, or even if one is necessary until you know what you are dealing with. When in doubt, ask for help from an expert in your area. Good luck with your lawn, and happy hunting.