APHIDS INJURIOUS TO ORCHARD FRUITS. 31 



until large irregular bunches of twisted leaves occur. Later the 

 insects attack the shoots, sometimes thickly covering them. The 

 species infests currants, gooseberries, and flowering currants. 



SEASONAL HISTORY. 



The stem-mother hatches from the eggs early in the spring and 

 becomes mature early in May. She produces young which are all 

 wingless. These in turn produce young which may or may not be 

 winged. The winged ones take flight to some unknown summer 

 host, while the wingless ones continue the infestation upon the cur- 

 rants until nearly midsummer. In the fall migrants return to the 

 currants and produce 3^oung which develop into males and egg-laying 

 females, the latter depositing eggs upon the twigs. 



THE GREEN GOOSEBERRY APHIS.^ 



The green gooseberry aphis is a green species with white honey 

 tubes. It lives upon the underside of gooseberry leaves, which it de- 

 forms badly (fig. 21, e), and also upon the twigs. 



The seasonal history of this species has not been determined. The 

 winter eggs are laid upon the host plant upon which the stem-mother 

 develops. Wingless forms occur later than the stem-mother, and 

 winged ones also are produced upon the gooseberry. 



THE HOUGHTON GOOSEBERRY APHIS.^ 



A pale green species is sometimes found curling the leaves of 

 Houghton gooseberries. The winged forms are somewhat darker than 

 the wingless ones. The life history of the species is unknown. 



THE NEW MEXICO GOOSEBERRY APHIS." 



Another species is found on gooseberries in New Mexico. The 

 wingless forms (fig. 21, /) are green, while the winged forms have 

 black head and body, with green abdomen marked with some dark 

 bands or spots. Its life history is unknown. A variety of this species 

 is found in California, feeding upon the red currant. 



SANBORN'S CURRANT APHIS.* 



A small species of aphid occurs in the Middle "West and South- 

 west on Missouri gooseberries and cultivated currants. This is San- 

 born's currant aphis. The wingless forms (fig. 21, ^) are green, and 

 the winged forms have black head, bod}^, legs, honey tubes, and an- 

 tennae. The species is found in the spring in rather large colonies on 

 the underside of the leaves, which it causes to curl and twist. 



'^ Aphis sanhorni Patch. '^ Aphis neomexicanus (Ckll.). 



"Aphis houfjhtoncnsis Troop. * Aphis ribis Sanborn. 



