858 EXPERIMENT STATION RECORD. (Vol. 37 



biology of Tnrsonemus pallidus, made in a badly infested greenhouse at the 

 Oregon Experiment Station. 



This species is a very serious floral pest found as far east as Coniiei.-ticut. 

 and is thought to occur throughout the United States wherever cyclamen stock 

 is grown. In greenhouses in Washington and Oregon in several cases growers 

 lost tlieir entire stock of cyclamen during 1916 and it has been reported to in- 

 jure seriously chrysantliemuras and snapdragons. The distortion of the leaves 

 and the discoloration of the flowers are the most noticeable effects of its attacks. 

 The work of the mite resembles a gall on the older leaves as well as on the 

 young, developing leaves, but the older leaves are not generally attacke^l. The 

 continued growth of the damaged parts results in distortion of the leaves, giving 

 the plants a very dwarfed and shrivele<l appearance. Often the leaves become 

 very much thickened at the points immediately surrounding the injure*! parts. 

 When the infestation is severe, the plants appear ultimately so badly curled 

 and distorted as to be unsalable and they do not bloom normally. This mite is 

 supposed to be spread by the shipment of seedlings and specimen plants from, 

 one place to another. 



Technical descriptions are given of its several stages. In life history studies 

 no nymphal stage was found, the larva transforming to a quiescent .stage from 

 which the adult emerges. Oviposition took place over a long period, the eggs 

 being found from early November until the last of March. The eggs are laid 

 in ma.sses in moist, dark places provided by the curling and distortion of the 

 leaves of the cyclamen plant. The average length of the incubation porlod of 

 ten eggs at a temperature of about 70° was about 11 days. The average larval 

 period for 10 individuals for the active stage was about 7 days, the larvsp being 

 found from November to the last of March. The length of the quiescent stage 

 averaged 3.5 days for 10 specimens. The adults are present from November 

 until late spring, and it is thought that they may be found in the greenhouse 

 throughout the year. The rearing methods employed are briefly de.scrlbed. 



In discussing remedial measures it is pointed out that owing to the mites 

 liavlng an extremely primitive respiratory system fumigation is an unsatis- 

 factory measure and spraying must he resorted to. After the older plants 

 become badly infested there is not much hope of saving them as the mites are 

 usually concealed under the calyx and penetrate even to the inner flower parts 

 of the buds so that it is quite impossible to reach them, and it is advisable to 

 burn the plants and sterilize the soil. The stable nicotin extracts and tlie 

 volatile nicotin extracts, as hlackleaf 40, are practically identical so far as 

 killing properties are concerned, and used at the rate of 1 : 1,000 appear to be 

 the most satisfactory means of control. The application of the nicotin spray 

 containing a small quantity of soap should be started when the plants are 

 quite young and continued every 10 days until the flower buds are well de- 

 veloped and begin to show color. 



A list of 12 ref(M'ences to the literature is appended. 



A synopsis of the genera of beetle mites with special reference to the 

 North American fauna, H. E. Ewino (.4fJH. Ent. Soc. Amer., JO {1917). Xo. i. 

 pp. 117-132. flfjs. 6). — In addition to keys to the families, subfamilies, and gen- 

 era of Oribatoidea descriptions are given of 12 new genera. 



On the nymph and prosopon of the tsutsugamushi, Leptotrombidium 

 akamushi n. g. (Trombidium akamushi Brumpt), carrier of the tsutsuga- 

 mushi disease, ^I. Nagayo. Y. Miyagawa, T. Mitamura, and A. Imamura {.lour. 

 Expt. Med.. 2.5 {1917). No. 2, pp. 255-272, plx. ^i).— The mite here dealt with is 

 the carrier of the tsutsugamushi or kedani disease, an acute exanthomatous In- 

 fectious disease which up to the present occurs only in the northern coast dis- 

 tricts of Japan and in Formosa. The mortality from this disease, which closely 



