Pl clarify what you mean by extracting insect. If you mean collecting insects, you should visit desert area in different seasons and use insect traps.

if you ment collecting it , you may have to use traps such as light traps 

Dear Mahat,

To extract small insects hidden in plants you can use beating and/or deeping washing methods. The first one consists in using a large sheet of white paper or a clear plastic tray (an umbrella can be used for larger insects) put underneath a branch of the plant .Then you beat the branch (with a stick) and  you look for insects that fall down on the paper/tray. The second methods allows to get an exhaustive assessment of the sample of small insects inhabiting a plant. It consists in deeping leaves, buds and small part of branches in a bucket full of water + 1 or 2 drops of dishwashing liquid. You shake the bucket and wait for 30 minutes to 1 hour. Then you filter water using filters and you pick small insects (using binocular and camel hair brush for small arthropods).