For field samples, the hand shaker shown in these pictures is hard to beat and I would imagine these jars could be shaken by a simple machine. http://www.honeybeeworld.com/diary/images/2009/DSCF4899.JPG http://www.honeybeeworld.com/diary/images/2009/DSCF4897.JPG http://www.honeybeeworld.com/diary/images/2009/DSCF4889.JPG http://www.honeybeeworld.com/diary/images/2009/DSCF4902.JPG The jars are cheap and when we were doing the field samples, we went out with boxes of the jars pre-filled with alcohol and did the shakes, then lidded the samples and put them, back in the boxes to be re-examined in the lab. (note: if the alcohol is cold from sitting outside in a vehicle overnight, the mites do not come off the bees as readily as when the alcohol is warmer.) These shakers are designed for a 300-bee sample, but in my experience, counts are most consistent using 200 to 250 bees due to the screen size. Of course, for smaller samples, the calculations must be adjusted, and a smaller sample may not be as representative, so there is a trade-off here. These shakers are easy to make, but I would recommend using a jar of the same capacity, but with a wider mouth if such jars can be found. In my opinion, a slightly larger screen area would be better for the standard 300 bee-sample. The shaker shown in the pictures has about one inch of bees on the screen (300 bees) when draining the alcohol and mites through to the lower jar for examination. IMO, that one inch is the maximum thickness of bees that will allow essentially all the mites to flow with the alcohol under all conditions. Half that thickness of bees (1/2") would be better, and that can be achieved by simply doubling the screen area. These jars are 70 mm inside, but have a 63mm mouth. That small difference reduces the mouth to 80% of the area of a similar jar with straight sides. To double the mouth area from this model, a jar with a 89mm diameter mouth would be required, and IMO, would be more accurate. Nonetheless, these jars are plenty good enough for our purposes. FWIW, some people tend to think a larger sample should be more accurate and wash more than 300 bees, but the resulting mass of bees can act as a filter and prevent some of the mites from going through the screen with the alcohol, resulting in a false count. Bigger samples need a larger screen area. Back to the shaker table Actually all that is needed to shake jars is a deck of some sort standing on on four springs with a motor attached somewhere driving a shaft rotating at the desired frequency. If an off-centre weight is mounted on that shaft, the table will shake, the amount of shake being set by the amount of weight and the distance from centre of rotation. To vary the direction of the shaking and create swirl, the motor and shaft can be set at an angle to the table, possibly with a hinged assembly for adjustment. To generate a hard shake, an adjustable soft or hard restraint block can be added to provide a hard limit to the table movement in one direction, creating a "knock" Some sort of jar hold-down is necessary and could be as simple as a sheet of semi-soft foam on a board placed on top of the jars and fastened by some simple method. Perhaps the idea is design a shaking table that separates the mites from the bees so that there is nothing to do but count. That is a bit more difficult. *********************************************** The BEE-L mailing list is powered by L-Soft's renowned LISTSERV(R) list management software. For more information, go to: http://www.lsoft.com/LISTSERV-powered.html Guidelines for posting to BEE-L can be found at: http://honeybeeworld.com/bee-l/guidelines.htm