Livestock Insects–Horses

Horse Bot Flies, Common Horse Bot, Throat Horse Bot and Nose Horse Bot

John B. Campbell

Identification and Field Biology

Bot Flies – Common Bot Fly
The bot flies are about the size of house flies, have a large head and quite a bit of yellow coloring.  The common bot deposits eggs on the hairs of the chest, legs, belly and flank of horses.  The eggs hatch immediately when the horse licks them, and the larvae bore into the tongue and gums.  They migrate from the oral tissues to the stomach, where they attach to the lining to complete the larval growth stage.  When that stage is complete, they detach and are passed out with the manure, where they pupate, and in time, emerge as adults.  The life cycles of the other two species are similar.  The throat bot flies deposit eggs on hairs below the jaw.  These eggs hatch without stimulation and migrate to the gum area of the cheek teeth before migrating to the stomach, pylorus or duodenum.  Nose bot flies deposit eggs on the hairs of the horse’s lips.  The larva of this species penetrates the lip membranes in front of the incisor before they migrate to the stomach wall.

Animal Behavior and Economic Losses

Severe infestations of horse bots cause gastrointestinal stress, block the stomach outlet (causing colic) or rupture the stomach (causing death).  Gum and tongue inflammation and abscesses may result from infestations in the mouth.

 

Management Strategies

Cultural

Sponging the areas where eggs are attached with warm water will cause the eggs to hatch, and the larvae can be destroyed before they enter the mouth of the horse.

 

Chemical

Delay treating horses for bots until after the first hard freeze, unless symptoms of bot infestation are apparent.  Insecticides recommended for bot control are listed at the end of the chapter.

 

 

Categories: Livestock insects, Horses, Horse bot flies, Common horse bot, Throat horse bot, Nose horse bot

 

Date: 12/29/2002