1917] ECONOMIC ZOOLOGY — ENTOMOLOGY. 857 



The t-pecies was first noticed in America in New York in 1898 and described 

 by Banks the following year under the name T. pallidus. Previous to that time 

 a similar and apparently identical mite was described from cultivated verbenas 

 in Illinois by Garman, who attributed the spread of a "black rust" to it. In 

 Maryland it is fairly common in greenhouses and a source of injury to cycla- 

 mens, chrysanthemums, snapdragons, fuchsias, and geraniums. The author 

 records the discovery of a female of a species of Tarsonemus identical with 

 T. pallidus at College Park, Md., on linden trees, indicating that it may not be 

 confined to greenhouses. 



The injury to geraniums is sometimes severe, causing the leaves to curl, spot, 

 and drop prematurely. The injury to heavy-wooded varieties is less pro- 

 nounced. The presence of the mite is often first recognized by the appearance 

 of scorched spots on the underside of the leaves. Cyclamen ftowers are also 

 attacked frequently, the flowers withering and curling in much the same 

 manner as the leaves. It is most severe when the plants are crowded, the 

 Jeaves in contact, and the humidity high. If the plants are well spaced the 

 injury is seldom serious, and the mites disappear or are greatly reduced in 

 numbers in a short time. 



The eggs, which are laid during the night on the underside of the leaf or in 

 protected spot between the leaf and the main stem, were found to require 

 from 3 to 7 days for incubation at a temperature of from 68 to 77° F. The 

 larval stage of the female is divided into two periods, the first consisting of 

 an active period lasting 1.5 to 3 days and the second a quiescent or inactive 

 period lasting from 1 to 3 days. At the end of the quiescent period the insect 

 molts and the adult mite emerges, oviposition commencing in about 2 days. 

 The life cycle of a single reared male required 5 days for the egg, 2 days for 

 active larva, 3 days for quiescent larva, and 6 days for the adult, or a total 

 of 16 days. The species was found to be parthenogenetic, continuous gener- 

 ations being obtained, starting with a single egg or larva confined in glass 

 cells, which lived more than five months without the appearance of the male. 

 Its capacity to reproduce parthenogenetically is continued for at least three 

 generations and probably more. In regard to the rate of reproduction the 

 author concludes that with a minimum oviposition of one egg per day during 

 the egg-laying period and a maximuis of 12 eggs per female the number of 

 individuals should total 40 at the end of one month, provided no males ap- 

 pear. His method of rearing the mites consisted in the use of shallow con- 

 cave cells provided with a small square of lens paper and a piece of geranium 

 leaf. Farrant's medium proved to be the best for mounting specimens. 



Tests of the effect of various insecticides on T. pallidus are reported in 

 tabular form. Those tested and discarded because of injury to geranium 

 foliage include lime-sulphur 1 : 40 and 1 : 50, turkey red oil 1 : 30, carbon disul- 

 phid emulsions 0.5 to 5 per cent (with liquid soap), sodium fluorid, sodium 

 chlorid 10 per cent solution, kerosene emulsion, and Tak-a-nap soap 1 lb. to 

 20 gal. Injury from chromic and picric acids is slow in appearing, and it is 

 possible that a thorough watering of the plants on the day following treat- 

 ment will reduce injury to a negligible factor. Small tests with blackleaf 40 

 seem unfavorable on the whole, but it is thought probable that nicotin has 

 some repellent action and should prove valuable as a preventive. A stream 

 of water will dislodge this mite more readily than it will red spider, due to the 

 absence of webs. With geraniums the use of a stream of water as a control is 

 available because the leaves do not curl sufficiently to hide the mite as is the 

 case with snapdragons. 



The cyclamen mite, G. F. Moznette {U. 8. Dept. Agr., Jour. Agr. Research, 

 10 (1917), No. 8, pp. 373-390, pis. 2, figs. 6).— This is a report of studies of the 



