TWO COMMON ORCHARD MITES 
THE BROWN MITE. THE RED SPIDER 
By GEORGE P. WELDON 
The dry climate of Colorado favors the multiplication of mites, 
among the more common and troublesome of which are the two 
species treated in this bulletin. Throughout the year these two 
species have been found quite generally distributed in the orchard 
sections of the Western Slope, and in some localities their injury 
to fruit trees was quite severe. Very often both species are found 
on the same tree, and no little confusion exists among the orchard- 
ists in separating one from the other. 
Because of the prevalence and severity of these pests it was 
thought best to carry on some experiments to determine how they 
may best be controlled. The results of these experiments, along 
with a general discussion of the life histories of the two species of 
mites, are given in this bulletin. 
The mites are not true insects, having 8 legs when adult. The)’ 
are classified as an order of the Arachnida, to which class the 
spiders belong. 
the brown mite (Bryobia pratensis Garman) Plate I, Fig. i. 
Life History 
There are three distinct stages in the life cycle of the brown 
mite. Beginning with the egg, a short account of each stage fol¬ 
lows : 
Most orchardists have seen the tiny red, globular eggs on fruit 
trees during the winter months, and are aware that they are the 
eggs of the brown mite. The winter is spent principally in the egg 
stage in Colorado. The over-winter eggs are deposited before the 
end of the summer season. This year practically no living mites 
could be found after the first of August, at Grand Junction or 
Delta, the eggs having been deposited previous to that date. On 
August 16, an occasional specimen of this mite can be found, but 
they are very rare and no more damage need be expected of them 
this season. The eggs are usually deposited on the trunk and limbs 
of trees, the crotches being favorite places. (See Fig. 7.) Often 
the bark is covered several layers deep with these eggs. By rub¬ 
bing one’s finger over the egg masses and crushing them, the bark 
of the tree may be made to assume almost a blood red color. We 
have found these eggs more numerous on pear, cherry, plum, prune, 
and almond than on any other orchard trees, the degree of infesta¬ 
tion corresponding to the order in which the trees are named. 
Shortly after the warm weather of spring comes on, the tiny little 
bright red, six-legged mites may be seen crawling over the leaves 
and branches. By the first of May they were abundant the past 
