13G MANUAL OF VEGETABLE-GARDEN INSECTS 



The date at which the melon aphis makes its first appear- 

 ance on cucurbits varies considerably from year to year, l)ut 

 in the northern part of its range it is usually rather late in the 

 season. Winged females fly or are blown into the field and, 

 alighting on a vine, crawl to the underside of a leaf and begin 

 feeding on the juices of the plant, which are extracted by means 

 of the insect's beak. The female begins to give birth to living 

 young at the rate of four or five each day and is soon surrounded 

 by a numerous colony of young lice. When about six days old, 

 these in turn reach maturity and begin to produce young. 

 After remaining on one leaf two or three days, the female may 

 move to another and found a new colony. The feeding of the 

 lice causes the leaves to curl downward, turn brown, shrivel 

 and die. When food becomes scarce, many of the wingless lice 

 crawl to the tender leaves towards the end of the vine ; these 

 in time succumb to the attack and the vine is finally killed or 

 stunted so that the crop is small and of inferior quality. A 

 large proportion of the lice of each generation acquire wings 

 while the others remain wingless. The former fly to other 



vines and start new colonies 

 of aphids. In this way the 

 whole field soon becomes 

 infested and unless the 

 aphids are checked by the 

 attacks of their numerous 

 insect enemies or killed by 

 artificial means, the crop is 

 sure to be destroyed. 



The wingless female is 

 about ^ inch in length, varying in color from yellow to green 

 or black, the eyes are brown and the cornicles black. In the 

 winged female (Fig. 80)^ the head and the greater part of the 

 thorax are black with the abdomen varying from yellow to 

 dark green. Breeding continues until frost. INIales and egg- 



FiG. 80. — Winded viviparous female 

 melon aphis (X 10). 



