26 GUAAI AGKICULTUKAL EXPERIMENT STATION. 



cattle nt that time of the year are usually in poor condition, due to 

 the absence of proper food and in many cases a shortage of fresh 

 Mater. A movement is now on foot to convert some of the old rice 

 fields into fields of Para grass to relieve this situation. 



Studies for determining the length of time required for the 

 engorged female tick to lay, for the eggs to hatch, and for the seed 

 tick to develop into a mature female after being attached to its host 

 do not show that the Guam tick differs essentially in its life history 

 from that of Margaropus annulatus. 



The effect of tick infestation on native cattle is in itself worthy of 

 consideration. An occasional excellent cart animal, which is fairly 

 well cared for and kept comparatively free of ticks, only demon- 

 strates what can be expected in cattle raising in Guam. Ticks are, 

 however, so widely spread on the island that few calves succeed in 

 avoiding serious infestations. This causes a decided check in the 

 growth and normal development of the calf and results in an under- 

 sized and undesirable animal. 



Native cattle badly infested with ticks show the following gen- 

 eral conditions: Body greatly emaciated, visible mucous membranes 

 anemic, and superficial lymph glands enlarged. The afflicted animal 

 will tremble violently when exposed to heavy rains. A disease which 

 is spoken of by the people of Guam as the " trembling disease " 

 probably is a result of tick infestation, judging from the description 

 of the symptoms and general conditions. 



The loss to cattle owners due to these ticks would be difficult to 

 estimate. The presence of thousands of ticks on an animal and the 

 irritation w^hich they set up result in weak, undersized cattle, influ- 

 ence the regularit}^ of their breeding, and materially affect them 

 as milk producers. 



A rancher in the vicinity of Merizo has for years practiced selec- 

 tion in making up his herd of breeding cattle, and has, through native 

 methods, endeavored to keep down tick infestation. The result is 

 that he now maintains a herd of cattle superior to any other herd 

 which has been observed in Guam. A great percentage of the cattle 

 live in the interior of the island and never receive any special care 

 or attention of any kind. This has produced an undersized, degen- 

 erate breed, not averaging in weight over -100 pounds after maturity. 

 Tick infestation and inbreeding are probably largely responsible for 

 this condition. 



The effect of tick infestation on imported cattle is much more 

 striking. Certain conclusions may be drawn from a general survey 

 of the temperature chart of Willowmoor Red Rose during the past 

 fiscal year (fig. 1). The temperature chart fluctuates almost from 

 day to day, the limits of fluctuation throughout the year being be- 

 tween 99° and 108° F. This cow is infested with ticks about half 



