166 Zoology of Colorado 



is found on aquatic plants, but migrates to almond, apricot and 

 plum. R. grabhami Cockerell is found on Lonicera, and was 

 described from New Mexico, but Mr. L. C. Bragg found it at 

 Eldora, Colorado. The Green Bug (Toxoptera graminum Rondani) 

 is very injurious to cereals, and is reported by Gillette as causing 

 trouble in the vicinity of Boulder. Cerataphis lataniae Boisduval 

 is a very curious aphid, resembling a scale insect, found on the 

 orchid Cattleya labiata in a greenhouse in Boulder. The Dogwood 

 or Sunflower aphis (Aphis cornifoliae Fitch) migrates between 

 dogwood (Cornus) and Sunflower. The Grindelia aphis (Atarsos 

 grindeliae Gillette), infesting gum-weed, is very remarkable for 

 the absence of the tarsi, the terminal portions of the feet. 



Many aphids have been found fossil at Florissant, causing 

 us to marvel at the preservation of such minute and delicate 

 objects. 



Scale Insects and Mealy-bugs (Coccidae) 



The casual observer, passing through the country, is not 

 likely to notice the small sedentary insects called Coccidae. If 

 he is observant, he may see the white ovisacs of the cottony maple 

 scale (Pulvinaria innumerabilis) on maples and box-elder trees 

 in the towns. On close inspection of these, he will find that the 

 female insects are oval and scale like, but at maturity secrete a 

 great quantity of material consisting of waxy threads in which 

 the eggs are enveloped. This material constitutes the ovisac, 

 and looks like a tuft of white cotton. It readily adheres to any 

 passing object, and there can be no doubt that the scales are 

 spread from tree to tree through the agency of birds, to the legs 

 of which the waxy secretion, containing the eggs, readily be- 

 comes attached. The young scale insects, on hatching, are seen 

 to be minute objects with short antennae and six legs. They 

 crawl about for a short time and then, in the case of the majority 

 of species, settle down to a sedentary life, permanently fixed to 

 some point on the tree or shrub which they inhabit. The mealy- 

 bugs and similar forms, however, remain capable of locomotion 

 all their lives. 



Scale insects are very interesting to the biologist on account 

 of their peculiar structure and habits. Certain of them are more 

 than interesting to the horticulturist, for they destroy his trees. 



