Baits and traps for the control of tobacco and tomato hornworms


Material Information

Baits and traps for the control of tobacco and tomato hornworms
Physical Description:
Scott, L. B
Milam, Joe
United States -- Bureau of Entomology and Plant Quarantine
U.S. Department of Agriculture, Bureau of Entomology and Plant Quarantine ( Washington, D.C )
Publication Date:

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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 30284673
oclc - 779476427
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Full Text

September 1942 AGRICULTURE E-578


By L. B. Scott and Joe Milam, Division of Truck Crop and
Garden Insect Investigations


For many years the larvae of the tobacco and tomato hornworm moths
(Protoparce sexta (Johan.)) and (P. cjqitiemacunata (Haw.)) have been known
as important pests of tobacco in many parts of the tobacco-growing sections
of the United States, These hornworms are also important pests of tomatoes.

Hornworms injure tobacco by devouring large portions of the leaves.
The damaged leaves may be ruined for commercial purposes, or in case of
moderately light feeding the quality, grade, and appearance of injured
leaves are lowered. Where abundant, the hornworms sometimes defoliate the
tobacco plants. In Tennessee, Kentucky, Virginia, North Carolina. South
Carolina, Georgia, and Florida, where hornworms on tobacco are regularly
or periodically abundant, it has been estimated that damage hy hornworms
reduces the weight of the potentially marketable crop approximately 5 per-
cent annually, on an average. For the 10-year period 1929-38 the annual
farm value of the tobacco crop in these States was approximately $182,000,000.
A direct loss of 5 percent in the potential weight and value of this crop
because of hornworm damage amounts to approximately $9,600,000 a year.
This sum does not include the damage caused from reduction in quality, grade,
arid general appearance in the cured product of tobacco injured by horn-
worms. The losses from these causes are estimated to be at least equal to
the losses suffered from reduction in weight. In addition, it is estimated
that the cost of control operations against hornworms on tobacco, principally
by applying insecticides and by hand picking, entails an annual expenditure
of at least $1,000,000.

On tomatoes the hornworms feed on the fruit, as well as on the
leaves, and cause extensive losses in some tomato-growing regions. No
figures are available regarding the extent of such losses.


In searching for methods of controlling these hornworms on tobacco
in such a manner as to avoid the presence on the cured product of poisonous
cr otherwise objectionable residues incurred by the use of available insec-
ticides, extensive experiments have been performed in an attempt to deter-
mine the efficiency of baiting and trapping the parent moths of the horn-
worms, thus preventing them from laying their eggs on the plants.

Description of Baiting and Trapping Methods

Th-o bait ordinarily used to attract hornworm moths is isoamyl salicy-
late, a chemical with a penetrating and pleasant odor. This chemical is
plocc-d inside an assembly known as a "feeder" (shown in figures 1 to 4,
inclusive) Thp- feeder consists of a slip-cover can 5-3/8 inches in diameter
and 3 inches deep. It is painted medium dark green. In the center of the
top of the can is inserted a 1-inch vial filled with isoamyl salicylate,
provided with a loosely fitting cork and with a short length of wick which
permits the odor of the chemical to escape. Inserted equidistantly around
this vial in the top of the feeder, as shown in the illustrations, are
three small white funnels made of tin and shaped to resemble blossoms
of jimsonweed (Datura stramonium L. The color and shape of these blossoms
are imitated for this purpose because hornworm moths are attracted to and
feed in large numbers on the blossoms of this plant. The apex of each of
the funnels extends downward into and nearly to the bottom of the feeder.
The feeder is filled with a poisoned liquid consisting of a sweetened solu-
tion containing 5 percent of tartar emetic. The holes at the apex of each
of the funnels permit the poisoned liquid to enter the funnels,

The assembled feeders may be used with or without a screen wire hous-
ing, or trap. When the latter is used, two of the feeders are placed in-
side the trap in the manner illustrated in figure 1 to 4, inclusive. The
number and location of traps for best results has not yet been determined.
The hornworm moths are apparently attracted to the near vicinity of the trap
by the escaping odor of isoamyl salicylate and are then visually attracted
by the white funnels simulating jimsonweed blossoms. After entering the
trap the moths feed on the poisoned liquid in the funnels and are retained
within the trap until they die. When the feeders are used without a trap
they may be placed at a height of approximately 5 or 6 feet, on the tops of
posts. The disadvantage of using feeders alone, as compared with fet-dcrs
inside the traps, is that when feeders are used alone the hornworm moths ma,
deposit eggs on the tobacco plants after partaking of the poison ,and be-
fore they die, whereas when traps are used the moths are confined until
they die.

Construction of Traps

The most satisfactory type of hornworm moth trap developed thus
far is illustrated in figures 1 to 4, inclusive. This trap is 36" long,
34" high, and 24" wide, and is constructed of 3/4" x 1-5/8" wood strips


fastened at the corners by means of corrugalcc fasteners and 2-1/2" x 1/2"
flat corner irons. With these strips 5 rectangular sections are 'ua',: to
form the framework of the top 24" x 36", the two sides 33" x 36" each, I.-i
the two ends 22" x 33" each. Each end has one cross piece 191" lonGi locat-
ed 20" from the bottom. These sections are assembled by fastening the sides
and ends together with 2" round-headed wood screws, the corners being streng-
thened by angle braces. The top is hinged to the upper edge of one of the
sides. The baffle (figs. 1, 2, and 3, A), which hangs in the center of
the trap, is made of l/2"-mesh hardware cloth and is 19" long by 15" wide,
It is supported by No. 9 wire, so formed that the baffle hangs 5" below
the top of the trap, 4" from each side, and 12" from the ground,. Ti.. wire
support is formed into hooks which fasten to screw eyes on the sides of
the trap (fig. 3).

The top, the two sides, and the part of each end above the cross-
piece are covered with galvanized-iron scr, ening, having 12 meshes to the
linear inch. The lower part of each end is also covered with this material
cut and shaped so as to form a large funnel converging inward for a distance
of 8" to 'orm a circular opening 7" in diameter to serve as an entrance for
moths. This entrance is formed on a 7" steel ring around which the sc,-:er,
wire is folded and soldered to itself. The large outer opening of the fun-
nel is 20" high and 19L" wide and is tacked to the inside faces of the
lower part of the end section. The distance along the screen from the outer
opening to the inner opening, is 8" at the bottom, 9" at the sides, and 10"
at the top.

Two feeders (figs. 1, 2, and 3, B) are supported by a member
(figs. 1, 2, and 3, C) of 3/4" x 3" lumber resting edgewise, 1 inch from the
ground, on small wooden brackets (figs. 2 and 3, D) fastened centrally to
the bottoms of the inner faces of the two end sections of the trap. Each
feeder is held in position by means of two strips of galvanized band iron,
7" long and 111" wide, fastened to the upper edge of the 3/4" x 3" support
with a 1-1/2" round-headed wood screw. The screw passes through 3/16" holes
in the centers of the iron strips and is tightened sufficiently to hold
them at right angles to each other. These metal" strips are upturned at
the ends approximately 5/8" in order to hold the feeders in position. The
feeder is so placed that the top of the gree, can is in the same horizontal
plane as the bottom of the round inner opening (figs. 1 and 2, F) of the
entrance funnel and is spaced 5" from it. Thus the small, white, blossom-
like funnels of the feeders may be seein clearly by moths entering the trap.


Materials and cost of one trap (fig. 4) and its feeders are as

60 linear feet of 3/4" x 1-5/8" lumber ......... $1.00
3 linear feet of 3/4" x 3" lumber .................. 06
50 square feet of 12-mesh wire screen ........ 1.50
2 square feet of -"-mesh hardware cloth ...... .10
30 inches of #9 steel wire .................................. 03
14 inches of 1*" band iron .................................. .04
1 hook and eye ... ..................................................... 02
2 screw eyes .. ..... _..................... .......................... .. .01
20 21" x I" flat angle irons with screws ...... 30
4 angle braces with screws ................................ 08
8 2" ,cu.nd--headed wood screws ......................... 02
2 11" round-headed wood screws ..................... .01
P a in t ...................................... ........ ..................... 1 5

Feeders (2):
2 5-3/8" x 3" slip-cover cans .......................... .16
60 square inches of light-gauge sheet tin .... .15
2 1" vials ............ ....... ..................... ... ......... 04
2 #2 lamp wicks .............................. .02
2 co r s .. .. .. .. ........ . ............. .......... ....... ... .. . 02
Paint ................... .......... ............. .................. ..... 0 1

The labor of one man for approximately one day is required to con-
struct a trap and its feeders.

Construction of Entrance Funnels

The screen-wire funnels are made from patterns shown in guide books
published for tinsmiths and sheet-metal workers. Books of this kind are
available at mail-order houses or they may be obtained through any large
book supply house. A pattern for a cone having rectangular base and round
top should be used.

Trap Coloration

The results of tests with traps painted various colors do not show
conclusively that coloration is an important factor in determining the
effectiveness of a trap, although there can be little question that white
traps are considerably less attractive than those painted green, red, yellow,
brown, or black. Traps waited medium brown appeared to be somewhat more
effective 4.haii those painted bright yellow, shutter green, bright red, or
black, but this wa.s u.ot shown conclusively. It is suggested that traps be
painted medium brown.


Baiting and Trapping for Hornworm Control

Although the baiting and trapping of hornworm moths has not as yet
progressed to a point where its use results in an entirely satisfactory
control of these pests, this method is being improved upon each ye.Ir, and
on the basis of available data there is reason to believe that it can be
used to advant&.-,e in many localities, especially where the infestation is
light or moderate. It has already been demonstrated that in areas .of light
infestation the damage by horniworms can be decreased materially '.,,' the use
of baits and traps and that the employment of this equipment permits a
marked reduction in quantities of insecticides otherwise required to prevent
serious losses to tobacco from the feeding of hornworms. The hazard of
insecticidal residue is also reduced by this method.

Small-scale tests conducted in 1941 in an area of very light horn-
worm infestation indicated that 10 feeders filled with sweetened bait con-
taining 5 percent of tartar emetic, placed at regular intervals on the
borders of a 3-acre field, or 4 traps similarly placed around a 1-acre
field, were sufficiently effective to obviate the necessity of applying
insecticides. All other tobacco in the vicinity required the collection
of the hornworms by hand or the application of insecticides to protect it
from serious hornworm cOi,,age. Weekly examinations of 100 tobacco plants
taken at random in each of the fields where the feeders or traps were used,
as compared with similar examinations in two comparable fields where the
feeders or traps were not used, indicated that the traps and feeders were
very effective in protecting the plants from damage. The data obtained
from these fields, which indicate that serious hornworm damage may be
avoided in areas of light infestation, are summarized in table 1. No conclu-
sive data are available at this time to show the extent of protection af-
forded to the tobacco crop by the use of baits or traps.

Table 1.--Results from the use of baited traps in tobacco fields for horn-
worm control

Field I lumber of jPlants Eggs ILarvael Other
No. jAcres Treatment observations examinedlfoundifound treatment

1 3.0 10 feeders 6 600 13 90 None

2 1.5 4 traps 5 4/ 500 25 89 None

3 1.5 Check 6 600 29 330 Hand-wormed
every day
4 2.1 Check 6 600 103 184 Two applications
of lead arsenate;
hand-'wormed once

4/ Crop harvested prior to sixth observation.


Tobacco growers should not expect to obtain complete control of
hornworms by the use of baits and traps in areas of heavy infestation, but
it is believed that the use of this control method will reduce the infes-
tation, lessen the damage from hornworms, and permit the grower to use
smaller quantities of insecticide than would otherwise be necessary.

I* 36 "--->i

Figure 1.-Side view of hornworm moth trap. A, baffle;
B, feeder, C, feeder support; E, entrance funnel; F,
round inner opening of entrance funnel.

36 -

Figure 1.-Side view of hornworm moth trap.
B, feeder, C, feeder support; E, entrance
round inner opening of entrance funnel.

A, baffle;
funnel; F,

Digitized by the Internet Archive
in 2013


Figure 2.-Top view of hornworm moth trap. A, baffle;
B, feeder; C, feeder support; D, bracket for feeder
support; E, entrance funnel; F, round inner opening
of entrance funnels

-- 30

----- S"---
k ------- ,, ,------- >

L___ '___
fy ai^

Figure 3.-Details of the construction of the feeders,
feeder support, and baffle;. A, baffle; B, feeder;
C, feeder support; D, bracket for feeder support.

Figure 4.-View of assembled hornworm trap. Photograph
made from a miniature model approximately one-third
the size of the trap used in field tests.


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