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. Here they remain for 6 weeks 

 or more. 



Larvae then pass to various parts 

 of the stomach, and attach them- 

 selves to the lining. The greatest 

 number attach near the stomach 

 exit. 



Mature larvae release their at- 

 tachment in the stomach, pass to the 

 rectum, and attach again. They re- 

 main here 2 or 3 days, then release 

 their attachment and drop to the 

 ground. The total period for larval 

 development is similar to that for 

 the other two species (10 to 11 

 months) . 



DAMAGE 



Horse bot flies damage animals 

 indirectly and directly. 



Animals under attack may inflict 

 damage on themselves or on anyone 

 trying to handle them. Fright and 

 irritation caused by egg-laying 

 adults or newly hatched bots may 

 result in animals going out of 

 control. 



Direct damage is produced by lar- 

 vae feeding on the tissues of the 

 animal. 



Indirect Damage 



By -flies. — Animals fear the flies 

 and are annoyed by them. The com- 

 mon bot fly is the least annoying 

 of the three species, probably be- 

 cause 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 

 morning until late afternoon. They 

 walk about trying to get rid of the 

 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 

 barns or other shelters. Colts which 

 are heavily attacked may lie down 

 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- 

 controllable. Runaways commonly 

 result. 



By larvae. — Newly hatched bots 

 produce a severe irritation as they 

 burrow into the animal's tongue, 

 gums, or lips. The irritation and 

 itching caused by the young nose 

 bots is particularly severe. 



To relieve the irritation, animals 

 may stand at watering troughs, dip 

 their lips into water, and rub their 

 lips violently against the wall of the 

 tank. They may injure themselves 

 by rubbing their lips and noses on 

 the ground, fences, stones, or other 

 objects. 



Direct Damage 



The bots attach themselves with 

 spiny mouth hooks to the lining of 

 the animal's stomach or small intes- 

 tine. These attachments cause in- 



