Insects 163 



the previous sixteen years was not less than sixteen million dollars. 

 The Clover Leaf-hopper (Aceratagallia sanguinolenta Provancher) 

 is a broader and shorter insect, which also occurs on sugar-beets, 

 and sometimes seriously damages the small plants. It is also a 

 pest on clover and alfalfa. The Grape Leaf-hopper (Erythroneura 

 comes of Say) is an extremely small species which is frequently 

 abundant on Virginia Creeper, causing the leaves to wither. The 

 Chermidae or Psyllidae, the so-called Jumping Plant-lice, are all 

 small, with delicate wings. Many years ago, I had a capsicum 

 pepper plant growing in a pot in my house in Boulder. Presently 

 I noticed some insects upon it, and on examination they proved 

 to be a species of Chermidae which could not be identified. I 

 sent some to Karel Sulc of Bohemia, and he described the insect 

 as Trioza cockerelli (1909). Later on, D. L. Crawford placed it 

 in a new genus, which he called Paratrioza. We now find that 

 this insect is wide spread in the west, occurring on various plants, 

 but seriously injurious to those of the potato family, such as the 

 tomato. In California there are three broods in a year, so it 

 multiplies very fast. Essig calls it the Tomato Psyllid, and gives 

 a good figure.* A species of this family (Pachypsylla rohweri 

 Cockerell) produces galls on the leaves of hackberry about Boulder. 

 The Aleyrodidae or White-flies are often seen in greenhouses, 

 but also occur out of doors. The immature stages resemble 

 small oval scale insects, and often have a white fringe. The 

 adults are very small, with four white wings, which in some kinds 

 have dark markings. Tetraleurodes ursarum Cockerell is found 

 on the bear berry or kinnikinnick. Trialeurodes ambrosiae Cock- 

 erell occurs on leaves of a common weed of the genus Ambrosia. 

 In this, the wings are spotted with gray. 



Aphididae or Plant-lice 



Professor C. P. Gillette, Director of the Colorado Agricultural 

 Experiment Station, has long been known as one of the leading 

 students of Aphides or plant-lice. Owing to his researches, the 

 Colorado species are comparatively well known. In October, 

 1925, he informed me that he knew of 243 species occurring in 

 our State. Although some are serious pests, many feed only on 



*In»ects of Western North America, (1926) p. 219. 



