1. External Parasites of Livestock
Ms.Beasley

2. External Parasites
Parasite: an organism living at the expense of another organism or host.
Host: Animal which serves as a residence for a parasite.
External Parasite: Live outside of the digestive, circulatory, and reproductive systems or other internal organs of livestock.

3. External Parasites Types of External Parasites Ticks Mites Flies Lice
Bots

4. Ticks Hosts 2 types All types of livestock
Major threat to cattle and horses
2 types
Soft ticks: outer shell is soft
Feed rapidly and then leave host.
Hard ticks: outer shell is hard
Feeds slowly and takes a large meal.
Drops from host to lay eggs.

5. Ticks Hard Shell Ticks Lone Star Tick: in wooded and brushy areas.
Problem in the spring and summer
Gulf Coast Tick: found in gulf coast area
Problem in late summer and early fall

6. Ticks Soft Shell Ticks Life Cycle
Spinose Ear Tick: Attaches deep within the ear
Not a problem in Texas, it is a big pest in other states.
Life Cycle
Adults lay eggs that hatch into larvae
Larvae find hosts such as birds
Larvae becomes Nymphs
Nymphs attach to host (Livestock) and become adults

7. Ticks
Damage
Cause inflammation, itching, and swelling at the site of the bite.
Ticks suck animals blood which can result in anemia, weight loss, and even death.
Ticks can also create wounds that can become infected if not taken care of.
Spread diseases.

8. Ticks Symptoms Usually found by visual inspection.
Livestock will rub on objects, and sometimes carry their heads in an unnatural position.
index.cfm?event=sit...

9. Mites Hosts: All livestock 2 Types Life Cycle
Surface mites- Stay on the surface of animal
Burrowing mites-Burrow into the skin
Life Cycle
Spend entire life on host
Adult lays eggs that hatch into larvae
Larvae molt & become nymphs
Nymphs molt and become adults

10. Mites
Damage
Hair comes out and skin can become rough and crusty.
Also can be called mange or scabies
Symptoms
Falling hair and rough, red skin can become visible.
Animals will scratch on anything

11. Lice Hosts: All species of livestock
There is only one species that affects swine.
Spread by animal to animal contact
2 types
Sucking lice- larger and take blood meals
Biting Lice- feed on dead skin and feathers

12. Lice Life Cycle Adult female glues her eggs to hairs of host
Eggs hatch into nymphs
Nymphs become mature adults

13. Lice Cattle Biting Cattle Louse Short-nosed Cattle louse
Long-nosed Cattle Louse
Cattle Tail Louse
Little Blue Louse

14. Lice Hogs Sheep Hog Louse- Only species that feeds on hogs
Sheep Biting Louse
Sheep Sucking Body Louse
Sheep Foot Louse
Hog Louse

15. Lice Goats Horses Goat Sucking Lice Large, Yellow Louse
Angora Goat Biting Louse
Goat Biting Louse
Horses
Horse Sucking Louse
Horse Biting Louse

16. Lice Damage Blood sucking can cause anemia
Irritation and discomfort to the animal
Can cause decrease in appetite which leads to decreased weight gain
Can cause death if not taken care of.

17. Lice
Symptoms
Rough hair coats
Rubbing and Scratching
Irritated animal

18. Blowfly (screwworm) Hosts: All livestock Blowfly: the adult stage
Screwworm: larval stage
Life Cycle
Blowfly lays eggs around and on wounds
Eggs hatch into larvae or maggots (which feed on living flesh)
Larvae drop to ground & burrow in soil & pupate
Flies emerge after pupal stage

19. Blowfly (Screwworm) Damage Symptoms Causes weight loss
Permanent injury
Death
Symptoms
Unpleasant odor from wound
Enlargement of wound
Seepage of blood from the wound

20. Cattle Grub (Heel Fly)
Host: Mainly cattle, but they have been found on other species of livestock
Emerge in late winter, spring, or summer
Mainly a nuisance to cattle

21. Cattle Grub (Heel Fly) Life Cycle Adult fly lays eggs on hairs of legs
Eggs hatch into larvae which penetrate into the hosts body
Migrate until they reach the back
Grubs cut breathing holes & feed on fleshy skin
Reach maturity & burrow through the hide and drop to the ground
Grub goes into the ground and pupates
Fly emerges

22. Cattle Grub (Heel Fly) Damage Symptoms
Can cause economic loss from hide damage and decreased milk production.
Decreased amount of feeding time
Symptoms
Cattle run from the flies
Visible swelling of the grubs on the back of the animals

23. Horn Fly Host: Mainly cattle, but will attack other species.
Mainly a nuisance
Blood sucking species
Life Cycle
Female lays eggs in manure
Hatch into larvae that mature and pupate
Young flies emerge and become adults quickly

24. Horn Fly Damage Symptoms
Bites and sucks blood from the back, neck, head, and belly of the host
Can result in transmission of disease
Annoys the animal causing weight loss
Symptoms
Can be easily seen on the animals
They can cover an animal in the spring and summer

25. Other Flies Hosts: All species of livestock Other flies include
Horsefly
Stable Fly
Housefly
These flies bite and suck blood from the animals
Mainly a nuisance to animals

26. Other Flies
Life Cycle
Adult females lay eggs in manure, debris, and other dead decaying organic matter
Eggs hatch into larvae
Larvae mature and pupate
Flies emerge from pupae in about a week

27. Other Flies Damage Symptoms
Irritation from flies can cause loss of appetite and result in weight loss
Biting and sucking can cause transmission of diseases
Symptoms
Easily seen
Irritated animals

28. Horse Bots
Hosts: Horses only
Closely related to the heel fly

29. Horse Bot Life Cycle Adult fly emerges from pupae in feces
Females lay about 500 eggs on hairs of horses legs, stomach, neck, and chin.
Horse rubs or bites areas infected which stimulates hatching
Larvae enter mouth & migrate to the stomach
Larvae attach to stomach wall & mature
Mature larvae pass out of animal into feces

30. Horse Bot Damage Symptoms Can cause anemia
Reduce digestion when bots infest the horses stomach
Causes irritation to the horse
Fly is easily seen
Loss of weight
Sometimes scours
Irritated animal

31. Quiz Define Host What is an external parasite
List three external parasites we discussed today.
When you are finished please turn in your quiz.