October, '10] weldox OX MITES • 433 



distinct differentiation of the broods of B. pratensis, and while it is 

 quite a difficult matter to determine definitely this point, the fact that 

 at certain times practically all the mites in a certain orchard will be 

 adult, while at other times only the little red, six-legged nymphs, or 

 only the eggs will be seen in any numbers, would seem to indicate that 

 there is a more or less distinct separation of broods. 



This species of mite often deposits the eggs, which remain on the 

 trees all winter, before the first of August, and after that time scarcely 

 any mites can be found, and no injury need be expected from them 

 for the rest of the season. 



Control of B. pratensis. — The control of this mite is quite a 

 simple matter. Unlike T. himaculatus, which is not effectively^ con- 

 trolled by a dormant spray of lime and sulphur, this species is con- 

 trolled perfectly by such a spray. Many orchards which contained 

 a large number of eggs of this mite, both unsprayed and sprayed with 

 lime and sulphur, have been under observation since the time of 

 spraying in April, to the present date, August 4. In no case have 

 lime and sulphur-spraj^ed trees been found even moderately infested 

 with this species of mite. At most, only a very few individuals have 

 been seen upon sprayed trees. Three peach orchards, one not treated 

 with lime and sulphur, and adjoining orchards on two sides each 

 sprayed with " Rex " solution, were found to contain eggs in abund- 

 ance, and each was closely watched while the eggs were hatching so 

 that the effect of the lime and sulphur might be determined. It was 

 found that the eggs hatched upon both the treated and untreated trees. 

 On the former the mites would die in a short time after hatching from 

 the eggs, while on the latter development was unchecked. As a con- 

 sequence the unsprayed orchard soon had quite* a severe infestation 

 of mites, while the two treated orchards have been entirely free from 

 them all season. 



When orchards have not been treated with a dormant spray of lime 

 and sulphur it is often necessary to use a summer spray, and again 

 sulphur seems to be more effective than anything else. It was found 

 that only a few of the adult mites were killed by the sulphur, but that 

 the tiny larvae were destroyed as soon as they hatched from the eggs. 

 Consequently after the sulphur treatment, many adult mites maj' be 

 seen on the trees for a few days; for example, some pear trees sprayed 

 on July 1st, with sulphur, using 1 pound to 5 gallons of water, were 

 examined on July 5th, and manj^ adult mites were found on the foli- 

 age. On July 8th, not a single adult could be seen, and with the excep- 

 tion of an occasional newly hatched mite the trees were free from 

 them. Last season's experiments revealed the same facts in regard 

 to the sulphur treatment for mites, and in those states where trouble 



