666 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



A different species (Hypoderma bovis) is common in Europe and 

 has been found in Canada and several localities in the United States. 



There is, after years of study and observation of the ox-warbles, 

 still some difference of opinion as to how they get to their final 

 location under the skin of the back. The older view was that 

 the eggs were taken into the mouth where they hatched and 

 from whence the young larvae made their way directly into the 

 oesophagus. However, the facts as stated have now been es- 

 tablished beyond a reasonable possibility of a doubt and the older 

 oxplanation is therefore discarded since it was never actually 



demonstrated. 



The Sheep Grub * 



The third important example from the bot-fly family is the 

 sheep grub. The adult of this species is smaller than that of the 

 preceding but, like it, has some resemblance to a honey-bee. 

 Adults are present throughout the summer and lay their maggots 



(the eggs being hatched in the 

 body of the female) in the nos- 

 trils of the sheep. The larvae 

 then work their way up the 

 nasal passages and into the 

 frontal sinuses and sometimes 

 even into the brain. They 

 cause trouble familiar to sheep 

 men under the name of the 

 blind-staggers or gid. Symp- 

 toms are giddiness, or in- 

 FIG. 585. Sheep bot flies with larvae and ability to control movements 

 pupa. (After Riley.) naturally, loss of appetite and 



even death. The larvae remain in the head of the animal for as 

 much as ten months, being sneezed out at maturity. They pupate 

 in the ground and emerge as adults in some four to six weeks. 

 Remedies are difficult to advise. Prevention of oviposition by 

 providing darkened shelters for the daytime or by smearing the 

 noses of the animals with tar will be of value. Tar may be 

 renewed by the sheep in this way: Place small logs here and 

 there iix the pasture. Bore in these several holes with a two-inch 

 * (Estris ovis L. Family (Estridas. 



