12 CIRCULAR 10 6, IT. S. DEPARTMENT OF AGRICULTURE 



July to the middle of September. With her ovipositor the female 

 cuts the slit into which she deposits her eggs, one at a time, until 

 the slit is filled. All species except the dark-colored tree hopper 

 deposit an average of about 6 eggs per pouch, while that species 

 deposits an average of nearly 20. (Fig. 7, b.) Probably 100 to 

 200 eggs in all are deposited by a female of any of the species. 



HIBERNATION 



The insects overwinter in the egg stage in the outer wood of fruit 

 trees and possibly in other trees and shrubs. As much as nine months 

 of the life cycle may be passed in the egg stage, since the earliest 

 eggs are deposited by the middle of July and the latest hatching 

 does not occur until early in May of the following year. 



NATURAL ENEMIES 



Two species of parasites have been reared from the eggs of the 

 green-clover tree hopper (Stictocephala ine?" / mis). 8 Two determined 

 species of spiders 9 and other undetermined species, an ant, 10 at least 

 two species of lady beetles, 11 several undetermined species of 

 syrphus-fly larvae, and predatory lacewing flies 12 have also often 

 been observed devouring the hatching nymphs of this species. Cer- 

 tain mites are known to destroy the eggs of both Stictocephala 

 inermis and the dark-colored tree hopper, Geresa basalis. 13 Birds 

 and toads are also known to feed upon the tree hoppers both in their 

 nymphal and adult stages. 



PREVENTIVE AND CONTROL MEASURES 

 CLEAN CULTIVATION 



Since these insects are dependent in their developmental stages 

 upon the cover crop, such as alfalfa or sweetclover, or upon weeds 

 growing in the orchard, it is obvious that the removal of these 

 from the land before planting the orchard and keeping them out 

 continuously thereafter would be one of the surest methods of 

 control. 14 



It has been found that clean-cultivated orchards are always free 

 of tree-hopper injury and that injury is most serious in orchards 

 in which alfalfa is grown as a cover crop. Under the cultural con- 

 ditions prevailing in orchards in the arid regions of the Pacific 

 Xorthwest, however, it is inadvisable to keep an orchard clean culti- 

 vated although the land should be freed of any such crop as alfalfa 

 before the trees are set out. 



s Gonatocerus sp., Tetrastichus sp. 



9 Philodromas minuta Bks. and Dcndry pliant es militaris Hentz. 



10 Formica fusca fusca var. argentia Wheeler. 



11 Adalia oipunctata L. and Hyperaspis quadrivittata Lee. 



12 Genera Hemerobius and Chrysopa. 



13 Genus Achorolophus. family Erythraeidae. 



14 References to food habits and control do not apply to the crested, brown-mottled tree 

 hopper (Heliria rubidella) , which occurs in considerable numbers in the Wenatchee Valley, 

 Wash., since this species apparently feeds throughout its entire nymphal period upon the 

 fruit trees and is not dependent upon cover crops for its sustenance. Since this species 

 also deposits its eggs in the fruit-tree twigs, however, it is probable that all methods of 

 control other than clean cultivation, especially the use of dormant oil sprays, would prove 

 equally adequate for it. 



