It is important to estimate the number of persea mites per leaf to help determine the population level and its trend through time, since together these are used to make the pest management strategy and to evaluate the effectiveness of any pest control actions.
To get a quick but accurate estimate, collect at least 10 leaves of mixed age at random from the section of the grove you want to sample. Using a 10X to 20X hand lens, count the number of motile mites along the upper half of the second complete vein on the left hand side of the leaf. A complete vein is one that extends from the midrib to the leaf edge. A motile mite is one that has legs; do not count the eggs.
Total the number of mites from all the upper half veins of the leaves you counted and then divide this number by the number of leaves you counted to get the average. Finally, multiply this number by 12 to give you the estimate per leaf.
Example: If you counted 14 leaves your results might look like this:
2+6+14+2+10+7+3+5+6+4+0+1+3+7 = 70 / 14 = 5 X 12 = 60 mites / leaf
This may appear difficult but once you've done it you will
find it gives you a fast and efficient estimate of the population
in your grove.
* This method was developed by Dave Machlitt; see Machlitt, 1998 for details.