Figure 7. A typical cyathostome third-stage larvae (L3) viewed with a 40X objective lens. This micrograph demonstrates the L3 retained within the sheath of the L2 stage. This retained sheath protects the larva from dessication, but prevents the larva from continued feeding. The retraction of the L3 within the retained cuticle of the L2 is most easily visualized at the anterior or posterior ends.

Monahan, C. Anthelmintic Control Strategies for Horses. In: Bowman D.D. (Ed.), Companion and Exotic Animal Parasitology. Ithaca: International Veterinary Information Service (www.ivis.org), 2000; Document No. A0309.0500.(Accessed: 20 Nov 2018).