I wonder if you know the cycle for each type of worm?Here's the skinny on fecal tests. What is looked for on the slide, from either float or direct smear, are the worm eggs. Eggs are shed by the adult worms in cycles, so it is possible to have worms and have nothing show up in the feces. Usually it it best to do 2 tests, 2 weeks apart, if nothing is seen on the first test.