Each year, commencing in 1957, fine-wool Merino ewes that were born in 1954 grazed native and improved pasture from the time of weaning of their lambs (usually late January) until the end of the period when they were joined with rams (early June). For the remainder of each year, one group each grazed (A) improved pasture, (B) native pasture, and (C) a red clover (Trifolium pratense) pasture. Records of services, lambings, and birth and weaning weights of lambs were obtained each year until the final weaning in January 1963. Lambing, as a percentage of ewes joined, declined between 1957 and 1962 from 85–88% to 66% in groups A and B and to 25% in group C. An average of 89% of ewes that lambed each year conceived to the first service. This was not influenced by years or treatments. The total number of services recorded per group was greatest for group C. Birth weights were lighter and weaning weights were heavier for the lambs of group C when compared with those of groups A and B. Ewes that failed to lamb in any year tended to fail in successive years; hence the increases in flock infertility were due to ewes becoming sterile. A number of sterile ewes had cystic glandular hyperplasia of the endometrium.

Two groups of Merino ewes were observed for five years to determine the variation within years and to make comparisons between years in the numbers of ewes exhibiting oestrus, in fertility, and in lamb birth weights. A group of 35 ewes (continuous), was run constantly with vasectomized rams and services were recorded. From the other (changing) group, a fresh sub-group of 15 ewes was joined with fertile rams every four to six weeks; services were recorded, together with lambing performance and lamb birth weights.Distinct breeding and anoestrous seasons similar to those shown by other workers were observed in both groups of ewes. However, the onset of oestrous activity was a month earlier in the changing ewes than in the continuous ewes.Fertility was low during spring and early summer and reached a maximum in autumn.The birth weight of the lambs appeared to be predominantly influenced by the ewes' nutrition during pregnancy.

Host-seeking nymphal Amblyomma americanum (L.) (Acari: Ixodidae) were placed into heated water, and their survival or their torpidity was recorded as a function of exposure time. Exposures were determined that either kill the nymphs or affect their mobility. All nymphs died when exposed for a minute or more to a temperature > 51 degrees C. Nearly all nymphs remained motionless for a period of time when exposed for 3 min to a temperature > 44 degrees C.