Bulletin 151, Truck and Garden Insects


178), the pumpkin bug (see under cowpeas, page 161), and the
big-footed plant-bug (see under potatoes, page 177).
 Hand-collecting is a comparatively simple matter as the
bugs are massed on the heads of the plants. One should use a
net, or a pan of kerosene. If the pan is held under the head
which is then given a sharp jar, most of the bugs will fall into
the kerosene and be killed.
 Other insects attacking sunflowers are: Red spiders (see
under peas, page 175; and cutworms (see under cabbage, page
137.)
 SWEET POTATOES
 SWEET-POTATO CATERPILLARS (Prodenia spp.)
 Several species of caterpillars are likely to attack this
plant, particularly during August and July. If not combated
they often defoliate an entire field. They are velvety-looking
caterpillars which belong to the cutworm family but have more
of the habits of army worms as they feed during the day, and
have a strong tendency to collect in colonies so that defoliation
commonly begins in one or two places in a field. Indeed, one
species, P. commelinae (fig. 106, A), is called "the semi-tropical
 army worm." The most common
 S:species, P. ornithogalli, is about
 2 inches long before it enters the
 ground to pupate. (Fig. 106, B.)
 In color it is a dark; rich, vel-
 vety brown, almost black. The
 life history of these caterpillars
 SA is similar to that of cutworms.
 SControl.-The quickest and
 : most thoro method of killing
 these worms is to spray with
 B lead arsenate, using 1 pound of
 the powder to 50 gallons of
 water. Two pounds of quick lime
FIG. 106.-Sweet-potato caterpillar added will prevent any burning
moths: oaa na added will prevent any burning
 moths: a, Prodenia commelinae;
 Srod rnithogalli. Natural effects. The spraying should be
 done in the early morning so that
the spray will evaporate quickly. A cheaper method is to dust
the plants in the early morning when the dew is on them. For
this purpose use a mixture of 1 part of the arsenate to from 1
to 3 of air-slacked or hydrated lime. This can be applied by