330 INSECTS ATTACKING STOCK AND POULTRY 



drive cows into a smudge before they could be milked. The 

 writer has had the sleeves of his coat so covered with mosquitoes 

 in the Red River Valley, Minnesota, that they presented a gray 

 color, the original color of the cloth being hidden. Swampy 

 pasture land will always be a breeding place for this pest. 



Control. Stock can be protected, in a measure, by the follow- 

 ing mixture, frequently applied: Melt two quarts of lard and two 

 tablespoonfuls of coal tar, then add one quart of kerosene, one 

 teaspoonful of turpentine, one teaspoonful of oil of pennyroyal. 

 Apply with a rag, sponge, or brush. This is sufficient, of course, 

 to make application upon a few animals only. A number of the 

 strong-smelling compounds recommended in this publication for 

 use against flies on stock will temporarily protect the animals to 

 which they are applied. Man finds relief by applying oil of citron- 

 ella, for sale at many drug stores, anointing the face, back of neck, 

 and hands. One should avoid getting this too close to the eyes. 

 (See page 307, Insects Affecting Man and the Household.) 



The Scab Mite of Sheep. The scab, caused by the presence 

 and activity of the above-named mite (Psoroptes communis Furst, 

 var. ovis), is one of the most dreaded diseases among sheep-growers. 

 It is rightly said to be more injurious than any other disease 

 caused by external parasites. In many countries it is so important 

 that stringent laws have been enacted to check it. 



Life History. The scab mite (Fig. 332) is not a true insect, 

 but belongs to the class Arachnida, where we find the ticks and 

 mites, spiders and scorpions. In the adult condition it has eight 

 legs, in the young stage six. Its length of life is from three to 

 six weeks. The tiny eggs are deposited on the skin and under the 

 scabs on the skin, when they are formed. They are said to hatch 

 in from four to seven days. Every female lays an enormous 

 number of eggs. Moisture is conducive to their development. 



Injury. The first noticeable symptom of scab in sheep is a 

 scratching, rubbing, and biting by the infested animal, due to the 

 intense itching, particularly when the creature has become warm 

 by being driven or kept in a warm stable. This intolerable itching 

 causes the sheep to rub itself, and the wool, loosed by the scabby 

 condition of the skin, is rubbed off in patches (Fig. 333). The 

 coat of a scabby sheep looks rough, and the wool can be easily 

 pulled out in places. As the scab spreads, the mites are found at 

 the edges and the older points of attacks take on a characteristic 

 incrustated appearance. The incrustated appearance is due to 



