Clover mite (Bryobia pratensis Garman)


Material Information

Clover mite (Bryobia pratensis Garman)
Series Title:
Circular / United States Dept. of Agriculture. Division of Entomology ;
Physical Description:
4 p. : ill. ; 23 cm.
Marlatt, C. L
United States Dept. of Agriculture, Division of Entomology
Place of Publication:
Washington, D.C
Publication Date:
2d. ed.


Subjects / Keywords:
Spider mites   ( lcsh )
Bryobia praetiosa   ( lcsh )
federal government publication   ( marcgt )
non-fiction   ( marcgt )


General Note:
Caption title.
General Note:
"July 19, 1897"--P. 4.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 029679590
oclc - 406556998
System ID:

Full Text

Property of the United (.


. 1'nitetd St.It's l,)'Dpa rtment )f .\ri 'ilture,

SI'r,,,/,'ii prntrnfis tIarIiii .) --
I1.\l< \'TERISTICS ANI) METIII) !,1 *I T.~ ; .-- .- ._.
The suliject of this circular is a reddish-brown mite nhabout twice the
size of the orilin iry red m ite .,if,'. ti -, ,'i r ,.iii'., -, I'l.iiil-. It is ailout
three-hundredths. of an inch in length, oval, and %\ith rcnmirkahl 1,,.
anterior legs. (lther structural f,.itlir-. ,.- n, witIh li 1 1i ii
hairs hliih ,lthe iliIret parts of the body. are illustrated in the
accompanying liguru. which r,'1ir,-iit. much ,tiil.,id, thle lll .-_'r,,I
mite. vieeid tfr,,i, above and froni below.
This mit tirst -ame into ...pi, i.1 prominence as a d i-., .,1.l, invader
of dwelling IIl. 'I:,' about ten y:,irI since, but it had been known for a
number (f yv:Irs earlier as an iiinV of various fruit and shade trees
and forage plant-, its occurrence on iih' r. particularly ini thi Middle
Stat's.. I,.ing in, ticated in its -', i,-. 1it1i name, pra :,Iis and its con-
on1-0 n.fIiiIai f t lover m ite. It f.1lrl, to tht, family of '. 'I I i,1,e-
f'(ding ,It.. "Trr.inym liih ., which includes such ", deprc-
I d.ltars :is ti. r,.I -;aidlr -if ..'r'i.iliiiii, -..,ll, i,. referred t., and the
sqix-spitt>vd imit,.. which is iiliti troublesome to .1r ,i,.- in F-:. ii..,.
In 'alifornmi. mliere thi il.nt mitis p it s "-\"' iill. mischitivl 1. it ias
been vtrrv g,*.n.rally ,a'iiriiii 1 with the red spider, and in probaIl 'y
mist if th, reenrt',nr- to injury to deciduous trees ton the PI 11 Co st
by the' "re, s;pidi r" the r,.i1 Culprit is the in-sect under 1disussioin.
The pre-,ri ,if this mite on f,,lia._,'. either ,f clover or t rees, causes
th leaves t-1 .I ,ll,,>. or assume a -i, kly :i'pl r ir aS if attacked by
;a fungus. On t}ie tender leaves -if clover, notably on thbe ,i, r0 side,
the juik ,S .ir ,'x r:ir'alr d. ,fti-n over irr'a.,1 ir, '. i,.li ,4 areas, im itat-
ing in :Lppe.r.ire the burrows f certain I, .i,-II.i,i ii larva'. Ti.'
uinst notable in, lic:tion,. hiwe',r, fit the i, of the mite is the


occurrence of the eggs massed often in such numbers as to completely
cover the bark at the crotches and branches and sometimes over the
entire surface of the trunk. These eggs are of rather large size, of a
reddish color, and are conspicuous objects. When mnuimrous the
decided color they impart to the bark leads to their ready di.,cuvery.
As out-of-door enemies they are injurious at times to .lover and
other grasses, including the true grasses, as blue stem, but it is to fruit
trees that their injuries are especially marked. Throughout thie Pacific
Coast and in the fruit districts of Colorado and other Western mountain
States the clover mite is one of the principal enemies of suchli deciduous
fruits as peach, prune, plum, apple, pear, almond, cherry, etc., and the
poplar and elm, black locust, arborvitae, etc., among shade trees. As
house pests they are troublesome from their presence merely in their
efforts in the fall to find safe hibernating quarters and ocv:isionally in
their spring migrations in search of suitable breeding grounds.

Attention was first drawn to this mite in 1879 at Washington, D. C.,
from its occurrence on the trees in the Department grounds and also
on clover on lawns. It has since been reported from numerous locali-
ties from Massachusetts to California. Northward it occurs in the East
in northern New York and Canada. East of the Mississippi it has not
been reported in the southern tier of States, the southernmost records
occurring in Tennessee and North Carolina.
On the Pacific Coast it is known from San Diego, Cal., to East
Sound, Washington; and at Las Cruces, N. Mex., it is a serious fruit
pest. In the Sierra Nevada Mountains in California and in the Rocky
Mountains in Montana it has been found at elevations of from 7,000 to
8,000 feet.
It is remarkable, therefore, for its ability to exist under marked
differences of temperature and elevation. Its wide distribution and
its occurrence in situations remote from settlement indicate that it is
a native species. It was first characterized scientifically by H. Garman
in 1,. 5, who proposed for it the common and Latin name by which it
is now known.
The wide range of this insect and the different climatic conditions
under which it exists lead, as might be expected, to certain variations
in its life history and habits in different localities. In the more
northern regions of its occurrence and. in the higher elevations it win-
ters in the egg state, the last brood, if it may be so called, maturing
in the fall, and depositing eggs on branches and trunks of trees some-
times in suifficient numbers to entirely cover the Iark two or three
layers deep. In 1,89 we received a mass of these eggs several layers

,l,,i, on a 1]'i,' ," of bark which the sMender st ates w a ,.,,, an area of at
Ir...t ,ii ,iii i,, feet ,I' -,- on the so flt 41ti 'i trunks ..I tt1 inwon(lH
gr'i' ii.L ait ai tclhvatim of from *' 1i (o NI I i di feIt I i,. waI in tlh1
SiIrr., N, '.iil.i M l, ,.i ni "l'. ,iIiiiiiii' (out yt f lt ani have hIad
:t .iiiil,, i[: r a cco tun t, w it hl +
.k i ii I I ti ii, MI I' r- t I I"
tlly .M ,,tiil.,i,,. in M.Xi,,, I ",t,
t N I
tl;in at about the Hsmn:: + j ,
,.I,.vation. In th li< l- I t

ill,. a ,il I':.,- rn S .t '-
Mlire the I. are In,- ,.
ilrictl f,,niinI on fruit 'i ,', 1 \", /
I~~ I L f
lrt., l,,y are s-ii.ill' '' ,
tIliti l to tle crotches i I C
:l l branches and are A 'I I I '
iiiil n,,:rlv so abundant. '.-,.' 1
In the colder r,-,i 1 I,-..
where the wi nter is E-
pis'cd in Mthe _,L state, !" -. ', "-- I
the issuanceof the ,, 'y," "7 "u
iIitvs the fll i L,' -: I" I" I'.
spring varies front May / -v f
until thle miiddle ,1, June, 'ri
depthiliing on the char- :'
acter of tli' season. In :''
thte warmer r,.i'i,~--.,-.
f,,r in-s n. ''. in the lati-
tuile ,,f \V.,t-l, 'i.t '',, 1
I). C+-- the m ites l,, i,L~ ". .+ ,1 '- 1
h, be noticeable on foli- .*':"'
iage and ,r.r- in M.iv or w... .
eairlir. and enter their .. [
hihernii inz quiarters : t r
early in October, in crev- '
iI'ce; of fences or ,.ill-.
or under the loose bark -
,if various trees. It jis 1
seven. th-,ref'r., that in "l
the warmer lie alit ,,, i l P -Br, ntb pn( i+ a dirsal viw; 6. virtral
tbr'e lile i is hlriillv inter- view: antl d, ilaw' : ?, +. rni u i artr A, '. I, +
ruptei during the win-
tr llmiOtlihs and the winter is pap:--.~I 1n1it,' as much in the active aIs in
the e... state. Tlroiuz'lnut the sunlInler ', L are produced continu-, as with most other plant mites, with no p rti, ,lifT.r.tli.t tin
of broods.

!ii i Illlnli I~I 01BIi~ liiii 11111lill
3 1262 09216 4994
The habit of this mite of abandoning its feeding situations in the
fall to seek hibernating quarters elsewhere leads to its being a house
pest of no mean importance. This is particularly true wherever it
has been breeding on clover or other grasses near dwellings. From
such situations, particularly in the Mississippi Valley States, it often
swarms into dwellings through doors or windows, its small size ena-
bling it to penetrate wire screens with ease, to the very considerable dis-
quietude of the housekeeper. There are only a few records of their
fantvring houses in the East, and in the extreme West they seem only
to have been found on trees.
The protection of fruit trees from the attacks of this mite is com-
paratively easy where the winter is chiefly passed in the egg state, as
in Colorado and other elevated or cold districts. The experience of
Mr. C. P. Gillette in Colorado has shown that the eggs may be very
easily destroyed during the winter by applying kerosene emulsion to
the trees at about twice the ordinary strength, viz, diluted with five
parts of water. Spraying at this time is both economical and easy,
on account of the absence of foliage, and no danger will result to the
plants from the application. Such an application also in the warmer
latitudes'will be of almost equal value as a protection to fruit trees,
since it will reach what eggs there may be and also many of the mites
secreted in the cracks of the bark.
It is a much more difficult matter to protect clover and other grasses
from the mites, except as it may be possible to spray in winter the
trees, fences, etc., on or in which the mites may be hibernating, in the
vicinity of lawns.
Their entrance into houses in the fall may be prevented by spraying
the lower portion of the building, walls, etc., with pure kerosene as
often as need be and also spraying the lawns immediately about the
building with kerosene emulsion nine times diluted. The mites may
be destroyed after they have gained entrance to the house by the free
use of buhach or pyrethrum powder, burning brimstone, or spraying
with benzine, taking due precautions with the latter substance in the
matter of fire.
First Assistant Entomologist.
Serreffry of Agriculture.
W.\.HINI;TON. D. C., July 19, 1.97.