1040 Summary of Agricultural Experiments, [march, 



Effect of Lime-Sulphur Wash on Scale Insects (Michigan Agric. Coll., 

 Tech. Bull. No. n). — Lime-sulphur wash is recognised as being a special 

 rather than a general insecticide, and is recommended by entomologists 

 as being particularly effective against scale insects. Its action was 

 found to be peculiar. Unlike the other contact insecticides reported 

 on, no proof could be obtained that lime-sulphur wash had penetrated 

 into the tissues of insects. It appeared to have very little effect on 

 large insects having heavy chitinous walls, and even when applied to 

 a small portion of a very delicate body-wall, such as the body of a 

 covered scale insect, that part might be killed before the rest of the 

 body. 



Various theories were tested, but it was finally concluded that its 

 action on scale insects was due partly to the fact that it takes up 

 oxygen in comparatively large quantities, thus indirectly suffocating the 

 insect which it covers, and partly to its effect on the wax at the margin 

 of the scale. It was found that this was affected by the wash, with 

 the result that the insects were absolutely sealed in under the scale 

 covering. 



Diseases of Live Stock. 



Diseases of Live Stock (Board of Agriculture and Fisheries, Re\pi. 

 of Proceedings under Disease of Animals Acts, 19 10). — This report in- 

 cludes particulars of special investigations carried out at the Board's 

 Veterinary laboratory. 



Habits of Ticks. — During the last five years, ticks have been obtained 

 for experimental observations in connection with the part they play 

 as carriers of disease. In the course of these a considerable amount 

 of information as to their habits was obtained, and a summary of 

 this is given. The report deals with Hcemaphysalis punctata, which 

 occurs on both cattle and sheep in this country. The life-cycle was 

 found to be as follows : — (1) Hatching of the eggs takes place mainly 

 in July, and, to a much less extent, in August; (2) if opportunity 

 occurs, as it must in most cases, the larvae become engorged almost 

 at once, and moult to nymphae, mainly in August and September, and 

 to a less extent in October; (3) the nymphae fill themselves, given a 

 host, mainly in August, September, and October of the same year, 

 and a considerable proportion moult to adults from September 

 onwards ; many nymphae do not engorge or moult until the following 

 spring; (4) the engorged females do not as a rule start laying until 

 spring. Some may lay in February, but the majority not till May or 

 June. Whatever be the date of laying, hatching appears only to take 

 place after the beginning of July. 



While a cycle of 95 days from engorged female to engorged female 

 is theoretically possible, it is highly probable that in most cases the 

 actual period is about 290 days. It is suggested that when dipping 

 for the suppression of ticks (this, of course, does not refer to "keds," 

 which farmers sometimes erroneously call sheep ticks) is carried out 

 it should be done in April or May, and in October or November, as at 

 these two periods the greatest numbers are likely to be caught en- 

 gorging themselves at one time. To guard against dissemination of 

 ticks, dipping should be carried out before moving animals from an 

 infected country or district. 



