5 
fruits, strawberry, and purslane—but it attacks also clover, beans, 
beets, spinach, tomato, hops, and pear, and several ornamental plants, 
including hydrangea, begonia, ground ivy (Wepeta glechoma), Aca- 
lypha, and morning-glory. From its abundance on some of these 
plants it has received a number of common as well as Latin synonym- 
ical names, the former including cotton aphis, orange aphis, cucumber 
louse, and cantaloupe louse.“ It is frequently called also the ‘* black 
aphis,” especially in its occurrence in greenhouses. Mr. Pergande has 
found it feeding upon a large number of weeds, among which are shep- 
herd’s purse, pepper-grass, pigweed (Amaranthus), dock (Rumex), bur- 
dock (Arctium), dandelion, lambsquarters (Chenopodium), plantain, 
chickweed, button-weed (Diodia), mallow, dogwood (Cornus), and 
Jamestown or jimson weed (Datura). 
Since these aphides are not at all particular as to their food, when 
they migrate from their favorite plants they start colonies on nearly 
any plant that chances to be in their line of flight. The writer has 
seen asparagus and violet attacked, the latter grown in greenhouses. 
LIFE HISTORY. 
Attack to cultivated plants begins from early spring till consider- 
ably later, and is made by winged individuals flying from weeds which 
serve as alternate food plants. Infestation naturally commences earlier 
in the South than northward, and may be simultaneous with the appear- 
ance of the crop above ground. Soon after the plants have developed 
leaves a few winged aphides can usually be found, and these are the 
forerunners of myriads to follow. As often as a plant becomes 
exhausted of its vital juices by the sucking mouth-parts of innumera- 
ble aphides, winged individuals are developed which migrate to other 
plants, so that migration in the case of this species is carried on prac- 
tically thruout the season. Flight from one kind of food plant to 
another, or from one field to another, is caused also by disturbance 
from the abundant natural enemies of the insect. The great num- 
bers of this species sometimes suddenly discovered on melons, cotton, 
orange, and other plants are often due to enforced migration on account 
of the death of other food plants in the vicinity, such as might be 
caused by atmospheric conditions, or by the ravages of the aphides 
themselves, or of other insects. The removal of the crop on which 
the insect was at work will produce the same effect. 
NATURAL ENEMIES. 
There is perhaps no better example, among insects, of a common 
and widespread species being held in abeyance and limited to innoxious 
a@The synonyms include Aphis (Siphonophora) citrifolii Ashm., Aphis citrulli Ashm., 
Aphis cucumeris Forbes. It is still mentioned in literature as A. ewcumeris. 
