1. Adult nematodes found in the Lungs (bronchi) of ruminants ........ Dictyocaulus sp.
2. Adult nematodes NOT found in the Lungs of ruminants .......... Go to: 3 & 4

3. Adult nematodes found in the Abomasum of ruminants ........ Go to: 5 & 6
4. Adult nematodes NOT found in the Abomasum of ruminants .......... Go to: 9 & 10

5. Female nematode possesses a vulvar flap ..... Go to: 7 & 8
6. Female nematode does NOT possess a vulvar flap ........ Trichostrongylus axei

7. Female nematode's uterus is packed with a large number of ova ........ Haemonchus sp.
8. Female nematode's uterus contains only one or two rows of ova ........ Ostertagia sp.

9. Adult nematodes found in the Small Intestine of ruminants ........ Go to: 11 & 12
10. Adult nematodes NOT found in the Small Intestine of ruminants .......... Go to: 17 & 18

11. Adult nematodes possess a cephalic inflation and cervical striations ........ Go to: 13 & 14
12. Adult nematodes do NOT possess a cephalic inflation and cervical striations .......... Go to: 15 & 16

13. Female nematode's uterus contains extremely LARGE ova ........ Nematodirus sp.
14. Female nematode's uterus contains normal size "strongyle-type" ova ........ Cooperia sp.

15. Female nematode possesses an ovijector ........ Trichostrongylus sp.
16. Female nematode does NOT possess an ovijector ........ Strongyloides sp.

17. Adult nematodes found in the Cecum or Large Intestine of ruminants ........ Go to: 18 & 19

18. Adult nematodes are long and whip-like, with a small anterior and a thicker posterior ........ Trichuris sp.
19. Adult nematodes are straight, evenly thick and NOT whip-like .......... Oesophagostomum sp.