Saturday, March 13, 2010

USE OF A DICHOTOMOUS KEY FOR EASY INSECT ID

Now I can tell your eyes are already starting to glaze over and you are considering skipping reading this blog entry. DON’T!!! This is a really easy way to narrow down the possibilities when identifying an unknown insect.

According to Webster’s Dictionary, the word “dichotomous” simply means “the process of dividing a group into two parts, esp. mutually exclusive or contradictory groups”. Fine so far, right?

So let’s say you find an unknown insect-like critter in your garden. You can first ask yourself (or the bug), “Do you have 8 legs or only 6 (or maybe a whole lot)?” If the answer is 6, you know you have a true insect and not a spider or other Arthropod such as a centipede. Now look for wings. Are there 2 or 4? Only 2 wings would indicate a member of the fly family. Are the wings clear or scaled? Scaled wings are the type found on moths and butterflies. You can continue in this fashion until you are satisfied you have a handle on what the critter may be.

This process can be as simple or as complex as you wish depending on how closely you want to come to exact species ID. Depending on how specific you want to get with the insect, you can go as far as what kind of hairs it has on its behind! Using this key is a way to eliminate what it cannot be. It is similar to the way a physician will approach diagnosis of an unknown disease or condition. Doctors use clinical tests to rule out certain conditions the same way you can use a dichotomous key to rule out what the insect cannot be.

There are several good dichotomous keys I have found on the Internet. One I especially like is at the site of the Amateur Entomology Society. You can go to www.amentsoc.org/insects , click on “What bug is this?” then “key to adult insects”. Another helpful site is www.bugguide.net . This site has a pictorial key to help you match up similar shapes of insects.

So why not give it a go and see if you can use this simple process of elimination to ID your next unknown bug. You will be very proud of yourself and so will I!

1 comment:

  1. Dear Bug Lady,
    For my new comic mystery set at a fictional dude ranch near Bandera, one of my characters who has never been outside the Dallas city limits is terrified of bugs on her bunk bed. Another character has studied up and reassures her that the bugs she finds won't hurt her. what kind of bugs does she find? What does my kind character tell her to reassure her?
    Thanks!
    Nancy G West
    Author of award winners Nine Days to Evil and Forever Fatal. ngwestsbcglobal.net

    ReplyDelete