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ISSUED APRIL 1929
SLIGHTLY REVISED OCTOBER 1937

UNITED STATES DEPARTMENT OF AGRICULTURE
WASHINGTON, D. C.

CIRCULAR No. 51

THE CHINCH BUG IN RELATION TO ST. AUGUSTINE
GRASS

By R. N. Wrson,’ entomological assistant, Division of Cereal and Forage
Insect Investigations, Bureau of Entomology

CONTENTS

Page Page
NGCLOdUCHONMsS == 2a ae 1 Natural enemies of the chinch bug__ 4
Generalidescription= 222 S22. = Natural checks! === = A ap he Car 5
Importance of damage___________-- 3 Disease______ ie eee Ae 3)
Where and when injury occurs__-_~_ 3 EVAN ee ee Ba ERNE ett 5
Mannercotiminyuny 22 2 ee Se 3 Control measures ____--_~_ = ene. anes 5)
Plants attacked_____-~- Sa es 4 Watehfulness Epa LAS «i ae = 5
Stages and life cycle__-________-__-_ 4 Insecticides _____~ A le a 5
Number of generations.._.___-____-- 4 Cultural methods £2 > 22222272 2- 6
Hibernation! Sane ees ESPs RS ty 4

INTRODUCTION

Much damage is done by chinch bugs (Blissus leucopterus Say)
each year to St. Augustine grass (Stenotaphrum secundatum) im the
extreme southeastern portion of the United States. There, becauce
of its ability to grow on very poor soil, thrive in shady places, and
remain green at a comparatively low temperature, St. Augustine
grass is much prized for lawns, parks, and golf courses, the area of
which totals many thousands of acres. Injury to it by chinch bugs,
however, has become so severe that in some sections the growing of
this grass has been practically abandoned, in spite of the fact’ that
the chinch bugs may be controlled by methods that are simple and
easily applied.

GENERAL DESCRIPTION

Two forms of the adult chinch bug, the long-winged (fig. 1, 4) and
the short-winged (fig. 2), occur in Florida, and these vary in relative
numbers during the year. The wings of the long-winged form
reach almost to the end of the abdomen, whereas those of the short-
winged form are more or less abbreviated. The body is black and
almost one-fifth of an inch long; the wings are white with a black
spot on the margin of each wing of the upper pair, and the legs and
bases of the antennae are red. .

The eggs (fig. 1, A) are very small, long, and oval, the top being
squarely cut off and surmounted with four small projections or
tubercles. They are whitish at first, but gradually turn to amber

1 Resigned Noy. 20, 1916.
18091 °—37

2 CIRCULAR 51, U. S. DEPARTMENT OF AGRICULTURE

and later show red. The newly hatched bugs (fig. 1, B) have much
the form of the adults. At first they are yellow, but they soon turn
bright red, with a pale band across the abdomen. A few days before
becoming adults they change to a brown-black color, but retain the
pale band, which is partly covered by the wing pads,

FIGURE 1.—The chinch bug: A, Eggs of the chinch bug very greatly enlarged; B, C, D,
and £, first to fourth stages of the nymph or larva; F, last nymphal stage or pupa ;
G, adult female of the long-winged form, all greatly enlarged. (Luginbill.)

THE CHINCH BUG IN RELATION TO ST. AUGUSTINE GRASS 3
IMPORTANCE OF DAMAGE

Thousands of dollars are spent each year for replanting the St.
Augustine grass which, in spots varying in size from a few square
feet to several acres, has been killed by the chinch bug. This insect is
the only serious enemy of St. Augustine grass. However, the loss
is not confined to direct chinch bug i injury, but results also from the
replacement of this grass by less desirable grasses, which comes about
because of the expense and labor of continual replanting and the
unsightly appearance of the affected surface. In some districts the
planting of St. Augustine grass has been practically abandoned,
largely because of a general “lack of knowledge regarding effective
control measures.

WHERE AND WHEN INJURY OCCURS

Chinch bug injury occurs in all parts of Florida, bemg somewhat
more severe in the central and southern portions of the peninsula.
Apparently little damage is done to St.
Augustine grass in the other Southern States,
in Cuba, or in Puerto Rico. Lawns on high,
dry, sandy, or shell soils usually show damage .
first, probably because they do not retain mois-
ture and are, therefore, least able to withstand
the strain of an attack. Injury may occur at
any time from May to November and is most
evident during dry weather, largely because
such conditions favor the rapid multiplication
of the bugs, but partly because of the lowered
vitality of the plants.

MANNER OF INJURY

Chinch bug injury to St. Augustine grass
is first noticed in the dying out “ot the grass

FIGURE 2.—Chinch bug:
Adult female of | the in small spots which increase in size with more
Mavnined@about 13 ai, ox less rapidity and may finally cover a con-

ameters. . (Horton and siderable area. On account of the progres-

Satterthwait.) ; Coir sata :
sive nature of the injury it 1s sometimes called

pees. Several of these spots may start in a lawn and gradually
use. :

The type of injury of the chinch bugs and their destructiveness
are largely a result of their gregarious habits of feeding. Many
young and adult bugs collect at the base of one plant, draining its
juices until it withers, and then leave it in a body for the nearest
plant. The plants so attacked turn from green to a sickly yellow and
soon wither and die.

Weeds spring up where the grass has been, increasing the unsight-
liness of the affected surface, but often the St. Augustine erass will
gradually reoccupy the eround if given sufficient time. The common
practice is to replant the grass, but unless the chinch bugs are first
materially reduced in numbers the new plants in their turn are likely
to be killed.

4 CIRCULAR 51, U. 8S. DEPARTMENT OF AGRICULTURE
PLANTS ATTACKED

In the territory where chinch bug injury to St. Augustine grass
is severe no other cultivated plants are seriously attacked, although
the insect is known to feed on several wild and cultivated grasses.

STAGES AND LIFE CYCLE

Three general stages are recognized in the development of the
chinch bug, namely, the egg, the nymph, and the adult.

Eggs are deposited on the St. Augustine grass at or near the points
where it comes in contact with the soil, or they may be scattered about
the plants in the soil, The eggs hatch into nymphs, in Florida dur-
ing the summer in from 9 to 13 days, the average period of the egg
stage being 11 days. The nymphs require, on an average, 30 days to
reach maturity. They change color as already described and molt
four times before becoming adults. The time which elapses after
the adult stage is reached before the first eggs are laid ranges from
5 to 13 days, the average being 8 days. Thus the average length of
the total life cycle is about 49 days.

NUMBER OF GENERATIONS

Since the average length of the chinch bug life cycle is 49 days, it
is possible that in “Florida at ordinary temperatures there are five or
more generations a year. However, as the egg-laying periods extend
over a consider able time, the generations become badly mixed, and,
even in the spring, adults and all sizes of nymphs may be found

together.
HIBERNATION

In northern Florida the adult chinch bugs hibernate or become
dormant with the approach of cold weather. In the extreme southern
portion of the peninsula it is probable that the adults are active
during all but a few of the colder days of winter, Dry grass grad-
ually collects about the roots of St. Augustine grass, particularly in
the older law ns, affording ample shelter for the bugs’ hibernation
and rendering it unnecessary for them to leave their feeding grounds.
This fact is confirmed by the knowledge that the spring infestation
often starts where the injury stopped the preceding year. Spring
infestation may sometimes also start around the bases of trees and
palms, indicating that hibernation has been accomplished in these
somewhat sheltered places.

NATURAL ENEMIES OF THE CHINCH BUG

In the district where St. Augustine grass is grown the natural
enemies of the chinch bug, such as insects, reptiles, and birds, have
little effect in controlling outbreaks of the pest.

Probably because of the repugnant odor of the chinch bug, the
number and effectiveness of its enemies are not so great as with 1 many
insect pests. Among the insects known to attack it are lady beetles,
ground beetles, lacewing flies, ants, and some of its near relatives
among the true bugs.

THE CHINCH BUG IN RELATION TO ST. AUGUSTINE GRASS 5

The following birds have been mentioned by the Bureau of Bio-
logical Survey as eating chinch bugs: Bobwhite, prairie chicken,
chimney swift, Traill’s flycatcher, crow, red-winged blackbird,
savanna sparrow, tree sparrow, cliff swallow, tree swallow, brown
thrasher, Carolina wren, bluebird, flicker, kingbird, horned lark, star-
ling, meadowlark, seaside sparrow, song sparrow, barn swallow,
mockingbird, catbird, house wren, and robin. No fewer than 100
chinch bugs have been found in single stomachs of the bobwhite
and meadowlark, and in a single instance 200 were taken from the
stomach of a brown thrasher.

Although it has been shown that frogs will eat chinch bugs, it is
readily seen that they can exert but little influence toward controlling

this pest.
NATURAL CHECKS

DISEASE

Diseases, which in some part of the United States are often
effective in controlling the chinch bug, have not been found in the
district over which St. Augustine grass is grown, This is true in
spite of the fact that much rain falls during the summer and that the
humidity is high, thus, it would seem, creating particularly favor-
able conditions for the development of fungous diseases.

RAIN

Rain is undoubtedly the largest natural factor concerned in bring-
ing about the control of this pest. Although the adult bugs are little
affected by water, even when submerged for several hours or days, it
is a well-known fact that small chinch bug nymphs are readily killed
by rain. It is not unusual for rains to occur every day for several
days during the summer, and this gradual killing off of the young
nymphs eventually reduces the numbers of the insect until the injury
is negligible.

CONTROL MEASURES

WATCHFULNESS

Watchfulness for the first evidence of chinch bug injury, com-
bined with prompt application of remedial measures, will prevent
practically all loss from this pest. The damage commences in small
patches, as before described, and can be effectually stopped before
further injury occurs. A commonplace practice in some localities has
been to spray the grass with water, but in this way only the small
nymphs can be killed, and since more are continually hatching it
takes considerable time to bring an outbreak under control, as is
often demonstrated at times of continued rains. Cold has little effect
on the hibernating adults, and there seems to be no practical means
of destroying them in their winter quarters.

INSECTICIDES

The quickest and most effective way of controlling chinch bug
attacks on St. Augustine grass is by applying contact insecticides.
The most convenient and easily obtained of these for the average

6 CIRCULAR 51, U. 8. DEPARTMENT OF AGRICULTURE

householder are the common laundry soaps. These soaps applied at
the rate of 1 pound to 5 gallons of water, or a tobacco solution con-
taining 40 percent of nicotine, used at the rate of 1 part to 800 parts
of water, with 1 pound of soap to 25 gallons of the mixture, will
effect complete control if properly applied. These solutions, how-
ever, have no effect upon the eggs of the chinch bug.

It is important that applications of insecticides be made when the
first sign of injury is noted. As plants which are yellowing, and
probably the nearby plants, are the ones upon which the bugs are
most numerous, these should be very thoroughly treated. Insecti-
cides applied to the dead brown grass are largely wasted, as the
insects have already left this in search of more attractive food.
Usually a strip from 3 to 5 feet wide about the edge of an infested
spot contains a large majority of the chinch bugs present, but careful
examination of the grass should determine the extent of the surface
to be treated.

Insecticides can be applied with some type of sprayer or with a
common garden sprinkling can. The principal emphasis should be
placed on the thoroughness of the application, the best method being
simply to deluge the plants, since the bugs crawl quickly into trash
and loose soil for shelter. The best success has been obtained where
the insecticides were applied immediately after a rain or after the
affected ground had been well irrigated. One thorough treatment
will usually control an outbreak on any particular patch of ground,
but another application may be necessary 2 weeks later if a large
number of eggs have hatched.

A control measure which the Florida Agricultural Experiment
Station ?, recommends is the use of calcium cyanide. In applying
this, certain precautions must be taken to prevent burning the grass.
The insecticide should be appled in the middle of a clear day after
evaporation of dew and when there is no immediate likelihood of
rain, as it is necessary that the grass remain perfectly dry until the
cyanide has dissipated its strength. The cyanide should be applied
very evenly, after which it would be desirable to sweep the grass
immediately with an old broom so as to brush the insecticide off the
green blades down into the mat of dead leaves and stems, in which
the insects are present near the ground. This prevents burning the
foliage and also places the insecticides in direct contact with the
insects. Great caution should be exercised in using the cyanide,
as it is a violent poison. Those working with it should keep to
the windward of its dust, and the container should be opened only
where there is good ventilation.

CULTURAL METHODS

St. Augustine grass should be kept in a thrifty condition, by irri-
gation and fertilization if necessary, so that its increased vitality
will enable it better to withstand chinch bug injury. Resistance of
the grass to injury is increased, also, when the grass 1s not mowed
too closely during dry weather, and where attacks are imminent
mowing should be delayed.

°Florida Agricultural Experiment Station Press Bulletin 371, The Chinch Bug on St.
Augustine Grass Lawns.

ORGANIZATION OF THE UNITED STATES DEPARTMENT OF AGRICULTURE
WHEN THIS PUBLICATION WAS LAST PRINTED

Secrerammojeagriculture- 2-9 =. 52-2 Henry A. WALLACE.

Cia COUCLO Nr ee ee DE EY te ee M. L. Wiuson.

ASST SHO ILLMISICCT CLOT ite che ree ree ict Phir ee Harry L. Brown.

Dinectontop Extension Work. 2 "= 2 C. W. WARBURTON.

DORARICE OF LUORUCC ee ee Eo Be ae W. A. Jump.

DRGHCE OF LOPE De = sas ea Soh eee M. 8S. E1sENHOWER.

IDGRACOR Gi) JLOPSOMIC GS Sea a es ae W. W. STOCKBERGER.

Dy nCChGTROfmILCSCONCI Ie ee tet JAMES T. JARDINE.

SOLLGTLO Reps icp ER Mya ec Ay 2 Mastin G. WHITE.
Agriculiural Adjustment Administration____- H. R. Touuey, Administrator.
Bureau of Agricultural Economics____--___- A. G. Buack, Chief.

Bureau of Agricultural Engineering______.___ S. H. McCrory, Chief.
BurcauiojeAntmat Industry = 2 922. S225 JoHn R. Mouusr, Chief.
Bureau ojesvologca Survey= 252) 2 Ira N. GaBRIELson, Chief.
Bureau of Chemistry and Soils____________- Henry G. Knieut, Chief.
Commodity Exchange Administration __-__-__- J. W. T. Duvet, Chief.
BUnCOUOfe Day ANGUSti Ye Qa ae 2 ee a O. E. Rep, Chief.

Bureau of Entomology and Plant Quarantine. Linz A. Strona, Chief.

Office of Expersment Statvons_-..-- 22 == 4. | JAMES T. JARDINE, Chief.
Farm Security Administration. .-___--_=_-_ W. W. ALEXANDER, Administrator,
Food and Drug Administration____________- WaLTtEeR G. CAMPBELL, Chief.
PORE, SO WGGLS SAEs OES ee Beate ne heueaet ee ee FERDINAND A. Siucox, Chief.
BURCH ULOfMEloOme HCOnomics. 226. ye sie” Louise STANLEY, Chief.
LURID 5 oo 3 So a a CLARIBEL R. Barnett, Librarian.
BULCHUNOMMaLOni naustrys = ei. Freperick D. Ricury, Chief.
SGCOURO Ma OLUC VOCUS ae eee eae Tuomas H. MacDona tp, Chief.
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UCT iGP LSU OL 5S ae es ee eee et Wiuuis R. Greae, Chief.

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