836 



SCIENCE 



[N. S. Vol. XXXVI. No. 937 



(Eogue Eiver Valley) has been comparatively 

 recent. The writer found it for the first time 

 in the summer of 1910, but it was thought to 

 be of slight importance at that time and little 

 attention was given it. Since that time, how- 

 ever, it has been very conspicuous in many 

 pear orchards throughout the valley, and its 

 effect upon the trees was so noticeable this 

 season as to attract general attention. 



It is interesting to note that Parrott' makes 

 mention of it as very common on apple foliage 

 in the United States, but does not seem to con- 

 sider it a serious pest. However, he states 

 that " Epitrimerus pyri and Phyllocoptes 

 schlechtendali have been quite numerous and 

 appear to be more common here than on the 

 continent." However, he adds, " The be- 

 havior of these two species in the future is a 

 matter of interest, as both seem to have possi- 

 bilities of developing to greater economic im- 

 portance." In Science (N. S., XXIIL, 576) 

 he states that Phyllocoptes schlechtendali has 

 been detected only on apple foliage. How- 

 ever, the writer has noted that apple foliage is 

 not seriously attacked, while the foliage, ter- 

 minals of twigs, and frequently the fruits of 

 the pear are most subject to injury. In fact, 

 the presence of the mite on apple foliage seems 

 to be of little importance, as no serious in- 

 jury because of its presence has ever been ob- 

 served. 



In this district this mite seems to be of eco- 

 nomic importance to the pear growers. The 

 injury resulting from its presence in the pear 

 orchards is generally apparent during the lat- 

 ter part of June or early July. The foliage 

 has a peculiar rust or russet appearance on the 

 under side and is also somewhat curled, as 

 though by drought. There may be some slight 

 russeting on the upper side, but this is rather 

 uncommon. The terminals of shoots are also 

 attacked and have the same brownish appear- 

 ance of the under surface of the foliage. 

 Where the attack is serious, the whole tree has 

 a brownish appearance and the trouble has 

 been given the local name " rusty leaf " by the 

 fruit growers. During the latter part of July 



•Bulletin No. 283, New York Agricultural Ex- 

 periment Station, 1906. 



and through the month of August, badly in- 

 jured trees shed the foliage from their ter- 

 minals. The terminals have a somewhat 

 shriveled appearance, the epidermis being 

 brownish-black or black. Very often the in- 

 jured epidermis is cracked or broken, due to 

 the expansion of the growing tissue beneath. 

 The fruit is also attacked and is russeted and 

 cracked in the same manner as the terminals. 



The injury to young pear trees is usually 

 greater than to older bearing ones. Some- 

 times almost complete defoliation of the young 

 tree results before it has had its season's 

 growth, and besides the epidermis of the 

 growing shoots has been injured. Fortunately, 

 this mite is very easy to control. As in the 

 case of all of our economic species attacking 

 plants, the use of lime-sulphur, dry sulphur, 

 oil emulsions, etc., will completely control it. 

 Since it is a surface feeding mite producing 

 no galls, it would seem that there should be 

 no trouble in eradicating it. 



The writer wishes to thank Dr. Nathan 

 Banks, of the U. S. National Museum, for 

 verifying his identification of the species. 

 P. J. O'Gara 



Office of the Pathologist 

 AND Entomologist, 

 Medford, Oregon, 

 November 4, 1912 



A PARAFFIN BATH WITH CONCEALED THERMO- 

 ELECTRIC REGULATOR 



One of the disadvantages about the ordinary 

 paraffin bath is the exposed thermo-regulator. 

 By attaching a covered moat to the back and 

 one side of an oblong bath and inserting a 

 thermo-electric reg-ulator similar to one de- 

 scribed by Long' patterned after Mast"" there 

 need be no delicate and breakable parts above 

 the bath. 



The bath described is heated by two incan- 

 descent lamps, one a four-candle, the other a 



• Long, J. A., ' ' The Living Eggs of Eats and 

 Mice with a Description of Apparatus for Obtain- 

 ing and Observing Them, ' ' TJniv. of Cal. Pub. in 

 Zool., Vol. 9, No. 3, pp. 105-136, pis. 13-17. 



^Mast, S. O., 1907, "A Simple Electric Thermo- 

 regulator," Science, N. S., 26, 554-556. 



