102 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



When the plants are large or somewhat protected we have found this 

 species spending the T\dnter upon the leaves of red clover. While this 

 is a common louse in Colorado, and we have done a large amount of 

 collecting for plant lice, we have never found it established upon any 

 herbaceous plant outside the clovers. 

 Aphis setarice Thomas 



A rather common species infesting the plum as a winter host in Colo- 

 rado, and going to the grasses for the summer. We have taken it most 

 comm.only during the summer upon Panicum crusgalli, but also upon 

 Setaria sp. 



Aphis vihurnicola Gillette 



The sexuparse of this species come very regularly in large numbers to 

 the snowball, Viburnum opulus, every fall. Soon after the creamy 

 white sexual fem.ales have begun to develop, the males follow and later 

 the eggs are deposited about the buds and axils of small twigs. The 

 young of the stem-n: others all get wings and leave the snowball bushes, 

 but we have never been able to locate the alternate host where the 

 summ.er months are spent. 

 Aphis avence Fabricius 



We have, at least, two or three species of Aphis which occur upon 

 both the apple and some of the grains and grasses that belong to what 

 we have designated as the avence group. At present, we prefer to pass 

 this group by as we are not able to satisfy ourselves as to just which of 

 these species avence really is. 

 Myzus bragii Gillette 



This species spends the winter upon Elceagnus and migrates to the 

 Canada thistle, Carduus arvensis, as the summer host. It seems prob- 

 able that there are additional summer hosts, but we have not been 

 able to locate them. 

 Myzus persicce Sulzer 



This species passes the winter upon pit fruits, peach, plum and cherry 

 with an apparent preference for the peach. The spring migrants 

 go to a very wide range of summer hosts, some of the most important 

 of which are the cabbage and other cruciferous plants, potatoes, 

 tomatoes, beets, species of Rumex, Dianthus, etc. This louse is another 

 species that is able to continue its existence from one year to another 

 in protected places out of doors and in greenhouses. 

 Phorodon humuli Schrank 



Winters on the plum, and in Colorado we have taken it in some 

 numbers upon plum foliage throughout the year. The regular sum- 

 mer host is the hop. 



