SCIENCE AND INDUSTRY. 
then the eggs hatch in number. This appears to be the normal method 
of over-wintering. It must not be forgotten, however, that, even during 
the winter, a few ticks may be found maturing on cattle, and these 
sertainly assist in infecting the pasture. 
A few warm days succeeded by cold weather, especially cold nights, 
are very detrimental to tick development, since the warm weather 
stimulates hatching, and then the larve (or at least a percentage of 
them) succumb to the cold. Lary appear to be very susceptible to 
adverse conditions during the first day after leaving the eggshell. 
The following table shows the maximum period (Period B) elapsing 
between the dropping or removal of the engorged female cattle tick and 
the death of all the larve which hatch from its eggs, no food being 
supplied. It represents the maximum length of time during which an 
infected paddock would reed to be kept free of cattle or other animals 
capable of serving as a host for the tick. 
It should be pointed out that in many cases the figures are based 
upon a very small number of plots in which hatching has occurred, con- 
sequently such observations should be repeated if possible. The results 
given are being checked against the results obtained from ticks kept in 
tubes, but otherwise under natural conditions. 
An assumption has also been made that larval or “seed” ticks are 
not introduced from elsewhere by being accidentally carried by man (on 
his clothing), vehicles, various animals, e.g., dogs, marsupials, ground 
birds, &e., or by flood waters. 
It is noted that, out of the many thousand larve which hatch from 
the eggs laid by the ticks in a plot, a few larve have a very marked 
longevity, being able to continue their existence for many weeks longer 
than the other larve in the same plot. The results given below include 
such cases. 
Perron B (Maximum), 
— Brisbane. Woolooga. Toowoomba. | West Burleigh. 
January .. aus Fars 171 118 150 129 
February D4 at 2 159 133 189 163 
March... at. ry 141 131 185 ~ 204. 
April on te ie 719* 156 No data 189 
May os a es No data 149 No data 184. 
June we tes me No data 108 No data No data 
July a et Oy, 133 105 No data 143 
August... fy fee No data No data No data 122* 
September Ps Ee No data 59* {| No data 61* 
October .. a ie No data 47* No data 141 
November. . as ns 73* No data tke 122 
December Ao fet 217 90* No data 154 
* Very few data available. These figures are probably low. 
The total period during the summer months (November to March): 
was generally between four to five months in the case of _Brisbane,. 
Woolooga, and West Burleigh districts, and four to six months in. 
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