1.   Maturation of these arrested larvae seems to be linked with the breeding cycle of the host and occurs at or around parturition.

2.   Arrested larvae accumulate during the spring and where Type II disease has been reported it has occurred in late summer or early autumn.

3.   The environmental factors which produce arrested larvae in subtropical zones are not yet known.

4.   For the successful treatment of Type II disease it is necessary to use drugs which are effective against arrested larvae as well as developing larvae and adult stages.

5.   Ovine ostertagiasis responds well to treatment with any of the benzimidazoles or pro-benzimidazoles, levamisole, which in sheep is effective against arrested larvae, or ivermectin.