The Euonymus scale (Chionaspis euonymi Comstock)


Material Information

The Euonymus scale (Chionaspis euonymi Comstock)
Physical Description:
Sanders, James Glossbrenner
Government Printing Office ( Washington, D.C )
Publication Date:

Record Information

Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 29649517
oclc - 27901134
System ID:

Full Text


unitedd States Dep,

L. 0.

THE Eil'O)NI S S('A I.E.

I NI I il 'ii .I ,i k I'

The most serious u*niyv of Oi," it rii. II,' .ioi-v. anit N.i ri ti'- of
Euonymus in the ea..te rii 'nitd il Stati- i- tco nml i l, kit i a:- (lie
Euonymis -,taleI. TlihO inijurie.s 1r41IL.-ioIIId bi\- I II aitiMei. ,f I i' iI'St

Fio. I.-A twig o F r'l-.n niii- in.-I. initd with 1 i': r tl N,.,- ale i .'I : i

almoSt prcinldO the grwiiig of these 6.0 ';ittifl'l plants for l.d._L'"- and
borders, while the dire experiences iif some girlnir- hbve caused
them to ahandn.n .entii-tlY the i.i,
a First iles-rile l in tin .\nth i-al Report .t..i L ',r
1880, p. 313 (, 1 IS I i .
125197-Nti. 114-0M /

S o I raq

.*.a .N A S.. .* -. .. ''"*- --

AL szaa .L --- M.c 1W

, ,I .. r 1 r


. 40

.,.,.., .: -B...-.

The attacks of this scale insect are almost exclusively confined to
Euonymus, although it has been found infesting the common wild
bittersweet ( Celastrws scandeom), especially when grow ing in prox i in ity
to infested Euonymus. The native wild species of the latter plant
and the introduced and horticultural varieties seem to suffer to the
same extent from the attack of their common pest, and it is no
uncommon .iglht to see plants of our wild ;pvcies dying in the open
forests and woodlands.
In 1886 Lichtenstein reported that at Montpellier, France, this scale
was so destructive to EuonyLus that it rendered the cultivation of
that plant almost impossible; and more recently from Japan come
reports of serious injury to .i-,u,,iyi ,,,japonica.

This insect was first brought to the attention of the scientific world
in the Agricultural Report for 1is) by Prof. J. H. Comstock, then
U. S. Entomologist, who reported that it had destroyed nearly all the
plants of J't,,iny.ix lat'folia in Norfolk, Va. There are records of
its injury to Euonymus japonica, F. europwus, F. ,rad(licas, E. atro-
purpureus, variegated and other horticultural varieties of Euonymus,
and Celastrus scandens (bittersweet).

Records are at hand of the occurrence of this scale in the following
State-, and it no doubt occurs in manny others: Ma1sa1chusetts, New
York, New Jersey, Penns lIvanin, Delaware, Maryland, District of
Col umbia, Virginia, North Carolina, South Carolina, (Georgia, Ohio.
and California. It is also reported from France. Italy, and .Japan.

This scale is exceedingly prolific. A plant which becomes infested
is soon so completely covered that the attack results in its early
destruction. There are at least two broods each season, and a prob-
able third one in the Southern States.
A badly infested plant appeear- as if covered with snow, this condi-
tion being due to the presence of the enormous number of the pure
white male scales, which are more conspicuous than the brown female
scales. The photogr:iphli (fig. 1)of a moderately infested twig of varie-
!,'ated Euonymus conveys an idea of the general appearance of thi-
scale. Note the comparatively few, elongate-oval, brown female scales
as contrasted with the great number of the narrow, white, tricarinate
scales of the males.
As in all the scale insects of this class, the female Euonvnymus scale
is permanently fixed to one location except for a few hours or davy in
[Cir. 114]

tli,. irsIt larval -ta;A,. when it aIpI ar+ a a tiny yIellow iil. ,.t with "ix
h'gs. which arte at rtl'1diiil 1ifill' it realizes the adult -1:1,.. The male
an1l felial, larvwi are similar in the first .It, _i,'. hut later the male
taciii ii'-s a pLiL Oif" delicate ing. a i i' .i,,'- fro m its ih ,f U l' ii,,
a frI'c ii..,.-t which never fI' I, since its Ilmouth-part- are r(Iplace(d hy
extri piair., of f.
Thi folldhwint1 short technical descriptim with accoIpl)ai\ ill'..H illus-
trnatiii (ftig. 2) is appended for 4.iliii, ,I,,irij- or peir)ons who have
awvct-- to a conipmtind ill' iIt r "It,:

IFl.,. .. 'h,,n, r, |.i .,( |., i-.l-iim of adult fen ile F.,n ir111- cale ( in p
I In> ; -nli I
.'',r"/ ,.r i. ,.,-,i -Di;ark ironii, mitl, yellow ,.xuvi ., of lth-avv texture. convex,
lr>i.lT.r .o-lri,,rly. I.-icln-h, 1.75 to 2 mn. Ventral scale white, coilqdetely devel-
iq,'l, aittachel I- iipp,.r .cale alhui, the sides but free posteriorly.
,./ (, in,1./,.-I'ure %%hit., iuirillI.l sil.1, r.-tr, iiIy tricarinated, with yellow
exi\ia. ILength. I t, I '"" num.
Fem',h.--Br,,aile-t al liit thsegitcriLt :tiiIlta[i.,ri ig .IT)t'riort\ and pOlteriorly. Median
lohes and liil.s ,id1 -,.'nd nil third lobes serrulate and pointed, widely -i'.ar:nld.:
lobultce, o.f si, -m-l aindi third loes partel t th,, ase, I,. inner the ,r.
t;ilani mpInvs nipii]>ar:ai'.-ly short. Five ,r,,iij|- of paragenital .,r: median, 4-:*
anterir lateral. 5- : *. -terior lateral, "-I

For the contri f (if this pf-t two distinct treatments are A%\;iilail.,
viz. sumliner :ind winter each h ii: ,.. :mg.01% :11.11L:, andi dis-
ad\'Iiiitagtes. poisons (P iri-i. .Lrclr. etc.) are of no avail in
['idr i1 ]

combating scale insects which suck the juices of plants; instead, a
corrosive or oily contact insecticide is necessarily used.

All scale insects are protected by waxy covering, of different kinds,
except in the young larval stage, in which .-tage they are most easily
d.,t roycd by insecticides. The most effective treatment which is least
injurious to the plant is the use of kerosene emulsion sprayed with
some force on all parts of an infested plant at the time of the hatch-
ing of the young, using special care to cover thoroughly both sides of
all leaves and twigs. The time of first hatching of the young varies
with the seasons and latitudes, and extends from the fir..t of May to
the middle of June in different localities. Where no frost occurs the
dormant season is very short. Repeated thorough spraying of in-
fested plants at intervals of two weeks between the above dates should
effectively control this scale. Emulsioln .t longer thaii l' per cent of
oil should not be used on plants during the summer, el.e the foliage
might suffer.
During the winter season plants are dormantand are hible to withstand
stronger insecticides without injury. The deciduous species of Euony-
mus should be treated after the falling of the lhave.,, or during winter,
with a 25 per cent kerosene emulsion, or a solution of whale-oil soup
at the rate of 1 pound to a gallon of water. The evergreen species
and varieties can withstand -'2 per cent kerosene emnulsion during the
dormant season. Care should be used to prevent the collection of the
oily emulsion at the base of a treated p1;it. else injury may result. .:
Directions for the preparation of kerosene emul-ioln and the propor-
tions of the ingridient- are given below:
Stock solution (i66 per cent oil).
Kerosene (coal-oil, laminp-oil)-..-----.....-------------------............--------. gallons.. 2
Whale-oil or laundry soap (or 1 quart soft soap)..................... pound.. A
Water ..............------------------..----...--.-----------------...----------.. gallon.. 1
Dissolve the soap in boiling water, then remove fr', f/ 6 i' ',, add the
keroseneimmnediately, and thoOioghly igilato the n ixt ire until a creamy
solution is obtained. This can be done byv pouring the mixture into
the tank of a spray-pump and puimnping the liquid through the nozzle
back into the tank. This is a stock solution which must he diluted
before u.-ing. In order to make a 20 per cent eitiulsion, add to each
gallon of the stock solution about 2+ g:illon- of water and agitate thor-
oughly before u-iin_-. For a 2-i per cent solution add t., each gallon of
the stock solution 1j galloln, of water and agitate thoroughly. This
[Cir. 114]


strength will kill i large prer''itna,.r, of the hiliirii tin.r- f.iiiltI. with-
out injury I% he Ilniilt-.
If MIM gI fl;Lpllt liii '-:)p can be obtained the preparation of the emnul-
sion will Ih Nliv ipliliil. It ill be unnecessary to heat the solution,
since the kero -n \% ill combine readily with the nMphthii and soap i ridI
form a per'f.t,. 'idlI, milky -white emulion w hen the mixture is thor-
oughlly aiiiitttil. If naphtha soap is ii. l..d. double the amIIount( called
for hy the forimiiuli. and emulsify i4n i, tI (rain) water.
J .\. S W-: n+ I..',<()*,,
,,',./., /,t./,, ," f q'. l/r I/,l 'e.
WANIIIN [Cir. 11mi



13 I i i i i2 ~ 0 iHiD 5 i27 l2 l
3 1262 09216 5272

* *4.