55 



application of arsenical mixtures and the further fact that nearly all 

 feeding is done upon the under side of the leaves. The arsenicals, 

 however, seem to be our best means of destroying the beetles by 

 means of insecticides. 



Phytoptus sp. — There is a Phytoptus mite that seems to be steadily 

 on the increase in Colorado, which attacks the cottonwoods. As the 

 leaves open in the spring, reddish excrescences begin to form about 

 the buds and upon twigs and limbs, of a more or less reddish color, 

 that continue to enlarge in size during the summer. The year follow- 

 ing, additional growth may appear about the old gall and new ones 

 form. In early spring the mites within the chambers of the galls are 

 of a deep red color, while those that appear during the summer are 

 lighter in color. In the northern portion of the State these galls are so 

 abundant as to be very noticeable to passers-by when the foliage is 

 off. Some trees are literally filled with them, so that scarcely a twig 

 can be found without one or more of the galls upon it. 



Another peculiar development, as the result of Phytoptus attack in 

 the cottonwoods, takes place in the same trees, and may be due to the 

 same species, so far as I know. It is the transformation of the flower 

 catkins into large pendant masses, often 6 or 8 inches in length, remind- 

 ing one of a long slender cluster of grapes. An interesting thing in 

 connection with this abnormal growth is that the attack of the mites 

 causes the flower parts to revert into leafy growths, pointing to the 

 origin of the development of the parts of the flower. 



LEAF-CUTTER BEES. 



Until the present summer I have never heard of leaf-cutter bees 

 being abundant enough to seriously defoliate plants, but am told by 

 an intelligent ladj^ residing near Fort Collins, some 10 miles from the 

 foothills, that her rosebushes were so badly defoliated by them the 

 past summer that it was necessary to cover them during the day to 

 save any leaves at all. 



Mr. Caudell said that in the garden of W. M. Rysler, of Delta, Colo., 

 this season he saw a number of mature radishes, every plant of which 

 was completely killed by the minute false chinch bug (Nysius mmutus 

 Uhler), myriads of which at that time covered the entire plants. In 

 some gardens he saw a patch of potatoes much injured by the larvae of 

 Plusia hrassiccB. The injury was so striking as to be noticeable from 

 a distance, resembling the ravages of the potato beetle. These same 

 larv?e were infesting cabbage, cauliflower, lettuce, sugar beets, and 

 garden beets. 



Mr. Hopkins said that he had collected the galls of a CJiermes sp. 

 (which Mr. Pergande thinks maybe Chermes sibiricus) from the Sitka 



