Circular No. 1 14. 
 
 v.mlHi 
 
 I cited States hepartment of Agriculture, 
 
 BUREAU OK XNT 
 
 L. O. HOWAKI), Kutomologit 
 
 THE EUONYMUS SCALE. 
 
 matpit • uonymi ( Sotnstock. | ° 
 By J. '•■ Babdem, M. \.. Assistant. 
 i\n:i » i > i ( i in\. 
 
 The noosl Berious enemy <>!' the various Bpecies and varieties of 
 Euonymus in the eastern United States i> commonly known as the 
 Euonymus scale. The injuries occasioned by the attacks of this pesl 
 
 • .— a twig of. Bnonymni moderatel; Infested with Boonyi 
 
 almost preclude the growing of these beautiful plant- for hedges and 
 borders, while the dire experiences of some gardeners have caused 
 them to abandon entirely tl><> use <iff"tfWe4)l:int- for decoration. 
 
 "First described in the Annual Report oJ jU^^muis'^ micr . if .TftnrnUarc for 
 1880, p. :r " ~-*-~ ■~-^—_ _, 
 
 12607— No. 1 14— 09 
 
The attacks of this scale insect are almost exclusively confined to 
 Euonymus, although it has been found infesting the common wild 
 bittersweet ( ( 'elastrus scandens), especially when growing' in proximit}' 
 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 sight to see plants of our wild species dying in the open 
 forests and woodlands. 
 
 In 1886 Lichtenstein reported that at Montpellier, France, this scale 
 was so destructive to Euonymus that it rendered the cultivation of 
 that plant almost impossible; and more recently from Japan come 
 reports of serious injury to Euonymus japonica. 
 
 HOST PLANTS. 
 
 This insect was first brought to the attention of the scientific world 
 in the Agricultural Report for 1880 by Prof. J. H. Comstock, then 
 U. S. Entomologist, who reported that it had destroyed nearly all the 
 plants of Euonymus latifolia in Norfolk, Va. There are records of 
 its injury to Euonymus japonica, E. europa'us, E. radicals, E. atro- 
 purpureus, variegated and other horticultural varieties of Euon} r nius, 
 and Cdastrus scandms (bittersweet). 
 
 DISTRIBUTION. 
 
 Records are at hand of the occurrence of this scale in the following 
 States, and it no doubt occurs in many others: Massachusetts New 
 York, New Jersey, Pennsylvania. Delaware, Maiwland, District of 
 Columbia, Virginia, North Carolina, South Carolina, Georgia, Ohio, 
 and California. It is also reported from France, Italy, and Japan. 
 
 description. 
 
 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 appears 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 photograph (tig. l)of a moderately infested twig of varie- 
 gated Euonymus conveys an idea of the general appearance of this 
 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. 
 
 A- in all the scale insects of this class, the female Euonymus scale 
 is permanently fixed to one location except for a few hours or days in 
 
 [Cir. 114] 
 
tin- first larval stage, when it appears :» — :i tiny yellow object with -i\ 
 legs which are atrophied before if reaches the adull stage. The male 
 and female larvae are similar in the first stage, bul later the male 
 acquires a pair of delicate wings and emerges from its scale covering 
 u free insect which never feeds, since its mouth-parts are replaced by 
 exl ra ]>:iir- of eyes. 
 
 The following short technical description with accompanying illus- 
 tration (fig. 2) is appended for entomologists or persona who have 
 access t<> a compound microscope: 
 
 Fro. 2.— Photomicrograph ol pygldlnm of adult female Bnonymiu - 
 
 jinaJ). 
 
 of female. — I>ark brown, with yellow exuviae, of heavy texture, convex, 
 broader posteriorly. Length, l.7"> to 2 mm. Ventral Bcale white, completely devel- 
 oped, attached to apper scale along the sides bat free posteriorly. 
 
 ■ of male. — Pure white, parallel aided, strongly tricarinated, with yellow 
 exuvia. Length, l to 1.25 mm. 
 
 Female. — Broadest at fifth pogiuenl and tapering anteriorly and posteriorly. Median 
 lobes and lobnlee of second and third lobes serrulate and pointed, widely separated; 
 lobules of second and third lobes parted t>> the base, the inner always the larger. 
 (Hand spines comparatively short Five groups of paragenital pores; median. 4-+>; 
 anterior lateral, 6-9; posterior lateral, 
 
 REMEDIES. 
 
 For the control of t hi-, pest two distincl treatments are available, 
 viz. summer and winter treatment, each having advantages and dis- 
 advantages. Arsenical poisons (Paris green, etc) are of no avail in 
 
 [fir. 11J] 
 
4 
 
 combating scale insects which suck the juices of plants; instead, a 
 corrosive or oih r contact insecticide is necessarily used. 
 
 SUMMED TREATMENT. 
 
 All scale insects are protected by waxy coverings of different kinds, 
 except in the young larval stage, in which stage they are most easily 
 destroyed 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 }'oung varies 
 with the seasons and latitudes, and extends from the first of May to 
 the middle of June in different localities. "Where no frost occurs the 
 dormant season is very short. Repeated thorough sprayings of in- 
 fested plants at intervals of two weeks between the above dates should 
 effectively control this scale. Emulsion stronger than 15 per cent of 
 oil should not be used on plants during the summer, else the foliage 
 might suffer. 
 
 WINTER TREATMENT. 
 
 During the winter season plants are dormant and are able to withstand 
 stronger insecticides without injury. The deciduous species of Euony- 
 mus should be treated after the falling of the leaves, or during winter, 
 with a 25 per cent kerosene emulsion, or a solution of whale-oil soap 
 at the rate of 1 pound to a gallon of water. The evergreen species 
 and varieties can withstand 20 per cent kerosene emulsion during tin- 
 dormant season. Care should be used to prevent the collection of the 
 oily emulsion at the base of a treated plant, else injury may result. 
 
 Directions for the preparation of kerosene emulsion and the propor- 
 tions of the ingredients are given below: 
 
 KEROSENE EMULSION. 
 
 stuck Mil i it inn (66 per cent oil). 
 
 Kerosene (coal-oil, lamp-oil) gallons.. 2 
 
 Whale-oil or 1 an miry soap (or 1 quart soft soap) pound.. J 
 
 Water gallon. . 1 
 
 Dissolve the soap in boiling water, then remov< from tJu. ^'/v.add the 
 kerosene immediately, and thoroughly agitate the mixture until a creamy 
 
 solution is obtained. This can be done by pouring the mixture into 
 the tank of a spray-pump and pumping the liquid through the nozzle 
 back into the tank. This is a stock solution which must be diluted 
 before using. In order to make a 20 per cent emulsion, add to each 
 gallon of the stock solution about 2 T ' gallons of water and agitate thor- 
 oughly before using. For a 25 per cent solution add to each gallon of 
 the stock solution 1| gallons of water and agitate thoroughly. This 
 [Cir. 1H] 
 
strength will kill u large percentage of the hibernating females with 
 «>ut injury to the plant-. 
 
 [fa good naphtha Boap can be obtained the preparation of the emul- 
 sion will be simplified. It will he unnecessary to heat tin' solution, 
 .since the kerosene will combine readily with the naphtha and soap and 
 form a perfect, >-old, milk] -white emulsion w lien the mixture i- thor- 
 oughly agitated. If naphtha soap is used, double the amount called 
 
 for bj the formula, and emul-ifv in -oft (rain) water. 
 Approved: 
 
 d \mi.s Wilson, 
 
 Secrt i 'i nj of ' JLoricultiirt . 
 Washington, D. ('.. October 11, 1909. 
 
 [Or. hi; 
 
UNIVERSITY OF FLORIDA 
 
 3 1262 09216 5272 
 
 7-T.