588 PIROPLASMA BOVIS 



in from two to twenty days, and during the winter months in thirteen 

 to ninety-eight days. The eggs are small, elliptical-shaped bodies, 

 at first of a light amber color, later changing to a dark brown, and 

 are about one-fiftieth of an inch in length. As the eggs are laid 

 they are coated with a sticky secretion which causes them to adhere 

 in clusters, and no doubt serves the purpose of keeping them from 

 drying out. During egg-laying the mother tick gradually shrinks 

 in size and finally is reduced to about one-third or one-fourth of 

 her original size. Egg-laying is greatly influenced by temperature, 

 being retarded or even arrested by low temperatures. It is complete 

 in from four days in the summer to one hundred and fifty-one days 

 during the fall and the beginning of winter. During this time the 

 tick may deposit from a few hundred to more than 5000 eggs. 

 After egg-laying is completed the mother tick has fulfilled her purpose 

 and dies in the course of a few days. 



"After a time, ranging from nineteen days in the summer to one 

 hundred and eighty-eight days during the fall and winter, the eggs 

 begin to hatch. From each egg issues a small, oval, six-legged larva, 

 or seed tick, at first amber colored, later changing to a rich brown. 

 The seed tick, after crawling slowly over and about the shell from 

 which it has emerged, usually remains more or less quiescent for 

 several days, after which it shows great activity, especially if the 

 weather is warm, and ascends the nearest vegetation, such as grass, 

 herbs, and even shrubs. 



"Since each female lays an enormous mass of eggs at one spot, 

 thousands of larvae will appear in the course of time at the same 

 place and will ascend the near-by vegetation and collect on the 

 leaves. This instinct of the seed tick to climb upward is a very 

 important adaptation to increase their chances of reaching a host. 

 If the vegetation upon which they rest is disturbed they become 

 very active and extend their long front legs upward in a divergent 

 position, waving them violently in an attempt to seize hold of a host. 



"The seed tick, during its life in the pasture, takes no food, and 

 consequently does not increase in size, and unless it reaches a host 

 to take up the parasitic portion of its development it dies of star- 

 vation. The endurance of seed ticks is very great, however, as they 

 have been found to live nearly eight months during the colder part of 

 the year. 



"The parasitic phase of development begins when the larvae or 

 seed ticks reach a favorable host, such as a cow. They crawl up 

 over the hair of the host and commonly attach themselves to the skin 

 of the escutcheon, the inside of the thighs and flanks, and to the 

 dewlap. They at once begin to draw blood and soon increase in size. 

 In a few days the young tick changes from a brown color to white, 

 and after from five to twelve days sheds its skin. The new form has 

 eight legs instead of six, and is known as a nymph. 



"In from five to eleven days after the first molt the tick again 



