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THE TWIG GIRDLER
A Guide to Recogniti on
and Habits in Alabama
L.L. IHCHO
(

INTRODUCTION
T\\ IG GIRDLER- IS \PPROPRI x LL't NA\\ttD. becaulse it is indeed a Lirdler of txxigs of sC5 eral species of har dwxood trees. The beetle, a conimon member ot the lon(ghot ned xwood boi er faily. occurs ox cr much of the eastern and southern

l7T

United States from Nexx England to Texas and Atrizona. It is miost common in the South. and is foxund throughoutt Alabama wxherevxer its host trtees occur. Pecan. hickories, and petsi mmon

are the fawn01ed

hosts in the State. but ciim. hackberr), bassxxood. soulwxood. oak, honeN locutis dogxxood. and some frui I trees may be attacked. Girdline>
Summer

K

md

occurs

in

late

and tall, and i, done by the temale beetle in preparation for lax in eggs. Girdled xxicIs usuallx bieak and fall. Presenc on the Ilround of txxi es that Phto I. Girleed pitt S*romt 1f a ppear to hax e beeni 0 peca shadide tre, In set: chexxed ott (Photo I) ti-oii C/os uf t)/ te end! of a the outside is a good siun girdl/d i/g 1.
'H, cthe is an .- sociate Professo in the .- ubr a a lItCDnixcrsih Department (of I ntioiimiiig -Uncidere~c ch u'nlta. O)rde r ( oleoptera: I amikc Cerandh cidae.

Alabama Agricultural Experiment Station
that the irdici is or has been
actix e.

Actxvitx and habits ot the twxig- _irdler in Alabama hav e been noted and recorded pei odically over sexverad years. The follow ing is a description of the beetle, its habits. damage caused, and general seasonal cycle. DESCRIPTION OF LIFE STAGES There aire four life staLes: egg. lars a, pupa. and adult. Adults (Photo 2A, B) are -,ray ish browxn wxith a lipehtei bind) across the back, and 12-17 mm lo g ( v r g ateA collected g h n xxa 0adults ubut o s 15 n m).3 Coloi is neai that of bairk of host txwigs, thus adults nr

on trees are inconspicuous and
easily oxverlooked (Photo 28). Antennae (feelers) aie shIetl loneer than the bodx beetle, and I I secment. Eggcs l'low it ac hio
rate-oxval. about 2.5 mmn hoe
enK

,
AV

of' the h-

ntnica

-

(mean of 2() measured). td xwhite to cream in color. IThex aie found in the bark of tx\ gii died by the female.
i,_

Larxvae (Photo 4) are xxhfite. lee less gru1bs. 16-25 numhIn xxhen
fully

gioxxn.

They air

//tac ,e

of bc

ic

color1 10 /h1t a/ the bark 0/ 1/he

distinctly segmented. and taper towxard the rear.

Ii

or brnch in B. I
i

Pupae (Photo 5) ar e about as long as full gross

larx ae. They are bare (no

coxvering cocoon), and the antennae, legs. and ely tra (wingo coxers) are visible. Color is xxhite to cream buit becomes darker as pupae near the change to adulthood.
'O)ne inch equals about 25
mm.

The Twig Girdler: A Guide to Recognition and Habits in Alabama

Photo0 3. Ti11g 14 id&i (4g4 in the bark of
/)CC-fl tig1.

Photo 4l. Full-g'o in ii id/cr- larva: hiva is /prepaing toi fupi/ate caii has/0.p/igg d11C 1111 14 I/ie 11(4 /)Ciiid it ii it/ia o l(h~Cips).

LIFE CYCLE AND HABITS The twxig cirdler requires a full y ear 1k com~plete its life cycle. figure 1. Most & i this period is spent as larx ae tuni elin and feeding unheard and unseen in d~ gird led ixxigs on the -round. Adu i
begin~~~

~

A,

~

~

~ to aperdr-.tefrs ~ af0
often

September.

and

are

present
They teed

throu-hout much of the fall.

on liv e twxigs of host trees. removimg small patches of bark KPhoto 6) near ends P/oo 5. fit
11

1iiy//ei pupa.

Adults girdling and laying eggs Eggs Full-grown larvae

Early stage larvae

Aug.

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar. Apr.

May

June

hJuly
in

Figuren

1. Seasonia/ develCo/pmient andi(

general~ /i/e (~vC/e o/ t/ie tig

ir4 410/C

Alabama Agricultural Experiment Station

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Ir

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1 1[ r11h ,lr-l 7

oftwxigs. Damage from adult I cedinIe is, usually minor and often e~oeS unnoticed. Girdling and oxviposition begi n in mid-Scptembcf and may continue into Noxvember, figure 1. The female beetle cuts a V-notch comnpletely around the twxin. usually~ leax inc it attached to the branch by a core of wxood (Photo 7). Batrk adjacent to the girdle olften has sexveral transv erse markings. (Photo 7). been explained. These apparently are made by the girdling female: the reason or purpoSC has not yeCt Several hourS may be spent girdling a single twxig and one female may girdle sexveral. Diameter oftwxigs at the girdle is usually ar ound 910 mmn. figure ?A (range 6-1 3 mm for oxver 300 twigs measured at Auburn).

The Twig Girdler: A Guide to Recognition and Habits in Alabama Frequency of occurrence 120 1 0 - - - ---

5

80 70 6C 50 40 30
20

1A

20.

-

10 0 67 8 910111213 Twig diameter (mm) 56 7 891011 Twig diameter (mm)

Figurii cciiio

I egg n/ic//e

2. Diuincir oIcgin//cdt twigs (A) cut// tcein//c: MOu,( B) (it i/he out(u/ctcruincd/ onl tw igs withi i/ircc or morc ii/ic

L ength of sex cred txx igs x aries trom11 around 30 cm up to one mA1. Eggs are laid in the bark of girdled tw~igs. The female cuts a small pit or niche
(Photo 8) and inserts~ a singfle egg, under the bark in the bottom of the pit (Photo 3). The opening to the egg is then sealed wxith a substance secreted by the female; sealed sites tend to glisten. ON iposition niches are LisuallIy located at the hase of leaf buds 01 secondary twxi os (Photo 8). Bark below each niche otten shows crossxwise miarkings similar to those seen at the girdle (Photo 7,. ON iposition miay occur all along the length of twxigs, but its outermost extent appears to be limited bN tig icfameter. Of 200 tx ig~s examined, fewx egs xxcie found beN ond wxhere twxig diameter had decreased to less than 6 nun, figuire 2B. The number of
Naries greatly. Among 480 txwigs collected in Auburn and Lee County, the number of egg niches per twxig r anged fromi 0 to 17, but about 60c/ contained 3 to 6 niches. Giirdfed Mxills usually break and fall. bult a fewx max remain attached thrioughout the year (Photo 9).

eggs per ttxiic

Egs begin to hatch iin 20-25 day s (around October L. at Auburn). Ili Alabama,
430 cm equials one toot-: one meter ( m) is about 401inches.

Alabama Agricultural Experiment Station

d
Ilhf N. I h /~u oo IT/icall/i. eggs arlacicu (ii btixc'. o/ icaof/)c adsecondl./ burls pigs. Inset: Clsn /ccof
ond(Itox trig.

'
0]i/chic.

47

4
-

mnost eggs haitch durinc the fall: howev er, Iunhatched eggs hav e been found dui nc tinter into earl', March. ti lure I. Larv ae tunnel and teed in (cirdled twics throughfully most of the year, becoin g rctt n by nmid-August to mid-September. During deve lopment, tars ae cut s~mallI
cL/I

holes in xxails of tunneled twxigs to expel IFuil-groswni larv ae then ping tunnecls xxith

The Twig Girdler: A Guide to Recognition and Habits in Alabama
ne\\ l\ tinnred aduilts may

remain in larvxal tunnels for
several days before emerg-

ing.

Pupae and new' adults fr om about mid-

may be liond in txxigs on the (round
August

through September,

figure 1. D~uring the first half of September, new~ adults
and /rass e jected bI

th

fuilly "ow larvaitt. t

begin to chewx out of the old girdled txwigs and mov e to

and star t a newx cy c.

lix e host trees to feed. girdle, Only one cneration occurs each y ear.

DAMAGE Ty pically in Alabama. girdler daimage is most common ainong- young hickorieS in natural stands, and pecans and other hosts maintained as shade and ornamental tirees. Daimage is the result of girdl ing of twxi Cs, small branches, and stems by the adult femalc. er fi h Structures bey ond the giirdle die and usually> break and fill Among large established trees, girdl ing is confIined to small twxigcs in the pi phn re \\ Oh \clI dcxip~jv
IL1

, ., t

1/c t
1 JRw w
4 v r !M1.-r ?OVw

pica/clcnna c causal /n ,irdlcr: l t t ,ircllcd lcaclcr; t13 I /carer curd branches girdled.

Alabama Agricultural Experiment Station

among many results in little or no real damage. However, among seedlings, sprouts, and small, young trees, damage can be severe. In hosttrees of this size, stems and main branches of many are of the diameter (6-13 mm) preferred by females for girdling and oviposition, figure 2A. Girdling of these structures deprives the tree of all or much of its crown. As a result, trees may die, or, become stunted and severely deformed (Photo 11A,B).

SELECTED REFERENCES Baker, W.L. 1972. Eastern Forest Insects. U.S. For. Serv. Misc. Publ. No. 1175, 642 pp. Beal, J.A. 1952. Forest Insects of the Southeast: With Special Reference to Species Occurring in the Piedmont Plateau of North Carolina. Duke Univ. School of Forestry Bull. 14, 168 pp. Bilsing, S.W. 1916. Life history of the pecan twig girdler. J. Econ. Entomol. 9: 110-115. Knull, J.N. 1946. The Long-horned Beetles of Ohio. Ohio Biological Survey Bull. 39, Vol. VII, 354 pp. Solomon, J.D. and J.A. Payne. 1986. A Guide to Insect Borers, Pruners, and Girdlers of Pecan and Hickory. U.S. For. Serv. Sou. For. Expt. Stn. Gen. Tech. Rpt. 50-64, 31 pp.

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