39 



increase in number the leaves gradually turn paler and yellowish in 

 color and become stunted, and soon the whole plant succumbs unless 

 the proper remedies are applied. Cuttings or young rooted plants are 

 particularly subject to serious injury, and this is especially true in the 

 spring. At this time the mites multipty rapidly, and unless plants are 

 carefully watched the}^ are apt to become so badly infested that it is 

 only with extreme difficulty that they can be restored to their normal 

 growing condition. 



The mites injure the plants by suction, and when they occur in num- 

 bers, which they almost assuredly will do when plants are neglected, 

 the vitalhy of the plants is slowly but surely reduced by the loss of 

 their juices, and in time all of their functions are more or less deranged. 



In cases of severe attack, millions of red spiders can be found upon 

 the foliage of plants, and the webs, which are rarely observable at 

 ordinary times, sometimes stretch from plant to plant, and the mites 

 may be seen passing rapidly over them and congregating in swarms. 



The following list of food plants has been compiled from Professor 

 Harvey's article previously mentioned (1. c, p. 14-2): Clematis, mignon- 

 ette, pink, Indian mallow (Abutilon spp.), Pelargonium, Canary bird 

 (Tropceolium peregrmum) 7 beans, rose, apricot, Cuphea, Godelia, 

 Fuchsia, Passiflora, cucumber, muskmelon, Manettia, Bouvardia, fever- 

 few, Mimulus, slipper flower (Calceolaria spp.), Thunbergia, verbena, 

 sage, heliotrope, cypress-vine, moon-flower, morning glory, tomato, 

 pepino (Solammi muricatum), eggplant, pepper, wedding bell (Brug- 

 mansia arborea), castor oil plant, hop, calla, Boston smilax, and Easter 

 lily. 



Violets and roses are particularly troubled by this species of red 

 spider, more especially, as might readily be inferred from what has 

 already been said, when these plants are grown under glass. Peaches 

 have been injured by the curling of their leaves; squash, corn, cowpea, 

 raspberry, Aping tuherosa, strawberry, beets, hemp, and watermelon 

 have also been reported to be attacked. 



REMEDIES. 



Red spiders are resistant to fumigation either with tobacco or 

 hydrocyanic-acid gas, and only a portion of these creatures are usually 

 killed by the ordinary use of the gas in greenhouses. They are stupe- 

 fied for a time, but eventually recover. They are, however, extremely 

 sensitive to sulphur, applied either dry or as a wash or in connection 

 with other poisons, and to soap. 



Flowers of sulphur, mixed with water at the rate of an ounce to a 

 gallon and sprayed over infested plants, is of great value in the eradi- 

 cation of this pest; or the sulphur may be combined with a strong 

 soapsuds. For the application of this spray a force pump with spray- 

 ing nozzle is of course a necessity. 



