GREENHOUSE RED SPIDER. 181 



mites. Although this gas is deadly to plant life, its application as a 

 fumigant to rid empty greenhouses of red spiders is extremely useful. 



Many spray mixtures proved to be efficient in controlling actively 

 feeding mites, but did not affect those in quiescent stages of development. 

 For the control of all stages above the egg stage linseed oil emulsion proved 

 to be the most satisfactory. 



The control of the red spider may be accomplished by combining pre- 

 ventive and repressive measures. 



Clean culture, or the eradication of weeds and plants which harbor 

 mites during the winter period, either within or outside the greenhouse, 

 is by far the most vital means of prevention in cucumber greenhouses. 



Dispersion within the greenhouse may be hindered bj^ destroying plants 

 or parts of plants which harbor the initial infestation. 



Applications of linseed oil emulsion at weekly intervals during the 

 early life of the plant prove very effective if made with extreme care. 

 At least three applications must be made for an efficient control. 



By checking red spider infestation early in the season the producing 

 period of the plants is lengthened approximately one month. 



BIBLIOGRAPHY. 



The following bibliography includes only the more important economic 

 works on the red spider: — 



Britton, W. E., 1901. "Common Soap as an Insecticide." First Rept. State Ent., 



Conn., pp. 227, 278. (Red Spider Remedy, pp. 271-273.) 

 Chittenden, F. H., 1901. "Some Insects Injurious to Violet, Rose, and Other 



Ornamental Plants." Bull. 27, n. s.. Bur. Ent., U. S. Dept. Agri. (The Two- 

 spotted Red Spider and Control, pp. 35-42, Figs. 9-14.) 

 Chittenden, F. H., 1909. "The Common Red Spider." Ciro. 104, Bur. Ent., 



U. S. Dept. Agri. 

 Ewing, H. E., 1914. "The Common Red Spider or Spider Mite." Bull. 121, 



Oregon Agri. Exp. Sta., 95 pp., 30 figs. 

 Fleet, W. J., 1900. "Some Comparative Trials of Insecticide Pumps in Relation 



to the Treatment of Tea Blights and Experiments in the Treatment of Red 



Spider." Indian Mus. Notes, Vol. IV., No. 3, pp. 113-117. 

 GiJlette, C. P., 1889. "The Red Spider." Bull. 4, Iowa Agri. Exp. Sta., pp. 



183, 184. (Greenhouse Control.) 

 Glover, T., 1855. "Insects Frequenting the Cotton Plant." Rept. U. S. Comm. 



Patents, Agri., pp. 64-119, Pis. VI-X. (Reference to red spiders, p. 79.) 

 Harvey, F. L., 1892. "The Two-Spotted Mite." Annual Rept. Me. Agri. Exp. 



Sta., pp. 1.33-146, PI. III. (Original description of Tclranychus himacu^atus 



Harvey.) 

 Maynard, S. T., 1889. "Experiments in Heating Greenhouses." Bull. 4, Hatch 



Exp. Sta., Mass. Agri. College. (Reference on control of red spiders, pp. 



14, 15.) 

 McGregor, E. A., 1912. "The Red Spider on Cotton." Circ. 150, Bur. Ent., 



U. S. Dept. Agri., pp. 1-13, 5 figs. 

 McGregor, E. A., 1913. "The Red Spider on Cotton." Circ. 172, Bur. Ent., 



U. S. Dept. Agri., pp. 1-22, 12 figs. 

 McGregor, E. A., 1914. "Red Spider Control." In Journ. Econ. Ent., Vol. 



VII., No. 4, pp. 324-326. 



