Bulletin 151, Truck and Garden Insects


ten days of the time of harvest. By using zinc arsenite instead
of lead arsenate, one can still further reduce the likelihood of
danger to the consumer, since zinc arsenite is less poisonous to
man. The common idea that a cabbage "heads up" by the
leaves curling inward is a mistake. The head is formed entirely
by internal growth; in fact, it is but a big bud and is formed
like other buds, never by the folding up of leaves. Conse-
quently, there is no danger of the poison being carried into the
interior of the head and held there on the leaves.
 CABBAGE PLANT-LICE
 The common aphid on cabbage is the garden aphid or so-
called green peach-aphid (Myzus persicae), altho the cabbage
plant-louse (Aphis brassicae) (fig. 74) and the turnip louse
(Aphis pseudo-brassicae) are also found.
 The garden aphid is bright green in color and smooth,
 while the -others have a
 more mealy look, and the
 turnip louse is quite hairy.
 The character of the dam-
 S.. age, the life history, and
 the means of control are
 the same for all three
 species and practically the
FIG. 74.-Cabbage-aphis: a, Winged fe- same for all aphids.
 male; b, wingless female. Greatly en- Aphids suck the juices
 large. (From U. S. Bur. of Ent.)
 from the plant on which
they live, stunting its growth, causing the leaves to curl,
turn yellow, and finally, the plant to die. They multiply
with great rapidity, often beginning when only a week old
and producing several young each day. During warm weather,
which means the entire year in Florida, the individuals of
most species bring forth young parthenogenically, that is,
without mating between the sexes. Indeed, during that time of
the year males are usually not produced at all. Usually the
young are born alive and active, the eggs hatching before they
are laid. But with the coming of winter, in more northern
states, males and true females are produced and eggs are laid
which do not hatch until spring. Most individuals never acquire
wings, but from time to time winged individuals are produced
and spread the species from plant to plant.
 Farther north the green peach-aphid spends the winter in
the egg stage on peaches, plums, etc. The first two or three