264 TRANSACTIONS OF THE HORTICULTURAL 



A second less well-known o;euus, of the red spider family, also 

 contains destructive species. It is the ^enus Bryobia, and differs 

 from Tetranychus in having the front pair of leojs much longer than 

 the rest, and in having peculiar scale-like appendages over the upper 

 surface of the body. Two species described by the writer in the 

 14th report of the Illinois State Entomologist (pp. 73, 74) have re- 

 cently been found damaging clover and grasses in the meadows. 

 Their method of working is the same as that of the spinning mites. 

 The leaves and blades are punctured and deprived of their sap, and 

 as a result become of a sickly yellow hue. It is to be hoped that 

 they may not become generally destructive, since an effective appli- 

 cation of any known remedy, on as extended a scale as would be 

 necessary for an injured meadow would be extremely difficult and 

 costly. 



Still another Bryobia damages the plum trees in the Pacific 

 coast region, and probably others will be discovered on other plants. 



INJTJEIES BY TAKSONEMID^. 



These mites are not so well known as the others, having but re- 

 cently been brought to the notice even of entomologists. The first 

 record of their injurious work in the United States is given in a note 

 from Prof T. J. Burrill, and printed in the 12th report of the Illi- 

 nois State Entomologist (p. 142). He discovered that the black 

 rust of cultivated verbenas was caused by mites, which prove to be- 

 long to the genus Dendroptus. The evidence of the presence of 

 these mites is a crumpling of the leaves, especially the terminal ones 

 next the flower buds, and also a blackish rust due to peculiar knobbed 

 hairs like those often caused by mites of the following family. Af- 

 ter describing the injury done by this insect. Prof. Burrill says: 



" The agent is a mite which works in the surfaces affected, where 

 also it deposits its eggs and completes its development. When the 

 plants are removed from the house to the open grounds the enemy 

 accompanies them, and lives upon them during the summer, to be 

 transferred very often again to the house, with the cuttings with 

 which propagation is practiced. Much injury and consequent dis- 

 satisfaction occur. The living, crawling animal, with its sharp 

 mouth-parts, is much too small to be seen with the unaided eye on 

 the plants, and even with a good hand magnifier it requires good 

 handling, and perhaps special practice, to readily make them out. 

 But an affected leaf, under a compound microscope with an inch ob- 

 jective, may be found swarming with the mites in various stages of 

 development. They are killed by hot water at a temperature of one 

 hundred and twenty (120) degrees Fahr. The plants may be safely 

 immersed in such water for a half minute, and as this is practicable 

 for potted plants, a means of cure is accessible to all. Two species 

 of these mites have been described in Europe, and we find one on the 



