again. Eggs are deposited close to 
the skin, usually along the front 
of the upper and lower lips. _ 
One female can lay 160 eggs. 
Egg.—Black. Hatches in about 
2 days. Moisture is necessary for 
hatching, but apparently friction 
is not required. 
Larva.—Newly hatched larvae 
burrow through the lips to the in- 
side of the lips just in front of the 
teeth. 
weeks or more. 
Here they remain for 6 
Larvae then pass to various parts 
of the stomach, and attach to the 
lining. The greatest number at- 
tach near the stomach exit. 
Mature larvae release their at- 
tachment in the stomach, pass to 
the rectum, and attach again. 
They remain here 2 or 3 days, 
then release their attachment and 
The total 
period for larval development is 
drop to the ground. 
similar to that for the other two 
species. 
Pupa.—Similar for all three 
species. The pupal stage begins 
1 to 4 days after the bots bur- 
row into the ground. The outer 
skin of the larva hardens to 
form a protective coating —the 
| pupal case; this case is brown 
or black. Within the pupal case 
| the bot changes into a fly. At 
the end of the pupal period, 
which ranges from 15 to 70 
days, the fly emerges from the 
Another 
| pupal case and mates. 
life cycle begins. 
DAMAGE 
Horse bot flies damage animals in- 
directly and directly. 
Indirect damage is that which in- 
fested animals do to themselves or to 
human beings. It may result from 
fright and annoyance caused by egg- 
laying adults; it may result from 
irritation caused by newly hatched 
bots. 
Direct damage is produced by lar- 
vae feeding on the tissues of the 
animal. 
Indirect Damage 
By Fiies.— Animals fear the flies 
and are annoyed by them. The com- 
mon bot fly is the least annoying of 
the three species, probably because 
it does not fly toward the animal’s 
head as do the throat and nose bot 
flies. 
On warm, sunny days, when bot 
flies are most numerous, horses and 
mules on pasture fight the flies from 
They 
walk about trying to get rid of the 
morning until late afternoon. 
flies, constantly bobbing their heads 
as they walk. If this fails to prevent 
attack, they run. They may gather 
in the shade on high ground when 
the wind blows, or they may enter 
Colts, which 
are heavily attacked, may lie down 
barns or other shelters. 
near the older animals. 
While the horses are fighting the 
flies, they are unable to graze; after 
days of bot fly attack, they may lose 
weight and suffer from lack of proper 
nourishment. 
Men who go near horses being at- 
tacked by flies may be injured se- 
verely. Horses attacked in harness 
or when saddled often become un- 
BY 
