ECONOMIC ZOOLOGY ENTOMOLOGY. 855 



tories. habits, and nature of tho injury to Coloi'ado orchards caused by several 

 species of phmt lice with preventive and remedial measures. 



The woolly apple ai)his { Srliizonriira lanigera) is considered as serious a pest 

 in Colorado as the codling moth. The greatest injury to the tree is due to 

 the root attack, but direct losses are greatest from injury to the branches 

 and fruit. But little injury appears to be done to roots that are more than 

 10 in. below the surface of the soil, which fact should be taken advantage 

 of in setting trees. Succulent and rapid growing parts, especially grafts, are 

 said to be very susceptible. In Colorado the Missouri pippin seems to be worst 

 infested while Northern Spy is practically exempt. Care should be taken that 

 only clean stock be set out. Experiments were conducted with insecticides from 

 which the following directions have been formulatetl as to the best methods of 

 treatment : 



" Just before the buds open in the spring, spray very thoroughly with a 7 per 

 cent kerosene emulsion, black-leaf dip 1 lb. to 60 gal. of water (or some other 

 strong tobacco decoction) or a good whale-oil soap, 1 lb. to 6 gal. of water. 

 Spi-ay the entire trunk and also the ground .-ibout the crown of the tree. Imme- 

 diately after treatment apply a tanglefoot band over cotton so as to prevent the 

 upward migration. If the lice become very numerous at any time upon the 

 toi)s, spi'ay them forcefully with the 7 per cent emulsion, or black leaf, 1 part 

 in 70 parts of water. Root treatments are temporary in their effects. When 

 the roots become very badly infested, treat as above described with 10 per cent 

 kerosene emulsion, black leaf dip (1 : -W), 2 to .3 gal. to a tree, or, if the soil is 

 (piite open and porous, carbon bisulphid." 



The green apple aphis (Aphis pomi). which is one of the worst orchard pests 

 in Colorado, is the sitecies most commonly brought into the State in the egg 

 stage upon nursery stock. The Missouri pippin is said to be particularly at- 

 tacked by this species while the Northern Spy is rarely so. Experiments have 

 shown that oil emulsions destroy the eggs only at very high strengths. Lime- 

 sulphur mixtures have proven quite successful, however. Kerosene emulsions 

 one-fifteenth oil and black-leaf dip 1 part in 70 parts of water, are said to be 

 the two sprays most favoi'ed at the present time. 



The clover aphis (Aphis hnlcrri) ranks next to A. pomi in numbers as a leaf- 

 infesting species of the apple. Wliile it appears to have a tendency to accumu- 

 late in the apple blossoms, it is not as yet considered a serious pest in Colorado 

 orchards. 



The European grain aphis (Aphis ( Sipliocorimc) (irnur) has been found upon 

 apple, pear, and quince trees in the State but not in sufficient numbers to do 

 appreciable harm. 



The rosy apple aphis (Aphis pi/ri) has appeared in orchards of the Grand 

 Valley attacking the leaves and causing them to curl similarly to these affected 

 by .1. pomi. 



The sweet-clover ai)his iApliis lucdicttfiinis) while preferring certain legumes, 

 as sweet clovei's, locos, black locust, and wild licorice, lias been frequently found 

 early in the season ujton tender new shoots of the apple and other fruit trees. 

 It is not likely, however, that, the species will ever become a serious orchard 

 pest. 



Two peach plant lice, the green peach aphis (Uyzus persicw) and the black 

 peach aphis (Aphis prrsiccr-ninn) are considered. .1/. pcrsifO" is said to be 

 by far the most abundant peach louse in the State. This siH'cies is said to have 

 been reported in this country upon the peach, plum, cherry, and many succulent 

 I)lants under different names. ,1. prrsicxv-nigrr was first observed in Colorado 

 in 1005. While at present known to occur only in a few localities ou the west- 



79218— No. 9—09 5 



