SCIENCE AND INDUSTRY. 
The life history of the tick must be known in order to appreciate 
the steps which are being taken to combat and control its ravages. When 
the female tick becomes fully matured, she detaches herself from hex 
host, and falling to the ground, seeks some secluded spot, where she 
remains quiet for from two to ten days in summer, or from two to three 
weeks, or even longer, in winter; after which she commences to lay 
eggs. The number laid varies from about 2,000 to 5,000—the average 
being about 3,000. Those which hatch out vary from 9 to 98 per cent. 
Immature females also lay eggs, but in smaller numbers. These eggs 
appear as dark, reddish-brown, ovoid wax-like bodies, about one-fiftieth 
of an inch long, and one-sixty-sixth of an inch broad at their widest 
part, and they are very resistant to external influences. Moisture has 
but little effect upon them, consequently the spread of ticks by heavy 
rain washing the eggs from one pasture to another may occur. Pro- 
tracted exposure to direct sunlight destroys their fertility, but they are 
capable of withstanding the effects of low temperature (even 15 degrees 
F.) to a remarkable extent. Under favorable conditions, the eges pro- 
ceed to develop larval or “seed” ticks, the time required for which 
varies from a fortnight to three weeks or more, depending upon external 
influences, such as temperature, moisture, shade, &e. Warm, moist 
weather, such as that of our coastal areas, is most conducive to speedy 
hatching. 
Since each female tick lays an enormous mass of eges at one spot, 
thousands of larve appear in the course of time at the same place, 
ascend the vegetation, fencing, &e., and collect in masses ready to swarm 
upon any object that brushes past. They do not appear to display any 
discernment as to the object they attach themselves to, as is evidenced 
by their swarming on inanimate articles, such as one’s own clothing, 
blankets, &. Their parasitism is, however, so perfect, that, unless 
they attach themselves to a suitable host, no further development occurs; 
they soon fall off, and in time perish. They are very tenacious of life, 
and have been known to live for nearly eight months during the colder 
part of the year in America. 
Field experience suggested the possibility of this period being 
exceeded in our temperate and sub-tropical coastal areas, and to ascer- 
tain more definitely the life-history of the tick, research work, as afore- 
mentioned, was instituted. Professor T. Harvey Johnston, who carried 
out the investigation, has furnished a report which, save for the deletion 
of a tabular statement of the work at the experimental plots upon which 
his conclusions are based, is substantially as follows :— 
In August, 1917, the writer was asked by the Executive Committee 
of the Advisory Council of Science and Industry to carry out investiga- 
tions regarding the biology of the cattle tick, with a view to determining 
the length of time taken by the tick to pass through its different stages— 
especially the ege and larval periods—in different localities and under 
different conditions, preference to be given to certain matters, which 
included the following :— 
1. The period elapsing between the dropping of the engorged 
female and the commencement of hatching of the eggs 
laid by it. 
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