I have copied this answer from my answer of you other questions.  I have also attached a general protocol for rodent oral gavage.

This is super easy to do. You can use a regular dissection microscope and dissect the beetles (usually Tenebrio molitor for H. diminuta) in a watch glass with Tyrode's solution. Remove the thorax and a small portion of the posterior abdomen. You can then take a Pasteur pipette and flush out the cavity with the Tyrode's solution, and that will bring out most of the cysticercoids. You can then use a rodent oral gavage syringe to pipette up the required number of cysticercoids and clean Tyrode's solution to equal 100 microliters. Then anesthetize your rats and administer via oral gavage. Let me know if this helps.