SAN JOSE SCALE - LIFE HISTORY AND CONTROL 



G. L . Jensen 

 Department of Entomology 



San Jose scales (Quadraspidiotus pemiaiosus) have been the 

 object of numerous complaints during the past season. They are 

 small (about 1/12 inch across) disk-shaped insects which are just 

 discernible to the naked eye. Under the hand lens the disks reveal 

 a raised nipple-shaped spot near the center. 



All parts of the tree are attacked above ground level includ- 

 ing the trunk, branches, leaves and fruit. Usually, the bark or 

 skin of the fruit is reddened for a short distance around each of 

 the scales. This phenomenon is especially noticeable on young 

 trees and on new growth of old trees. Heavily infested trees show 

 a general decrease in vigor and the foliage is sparse. If infesta- 

 tions are allowed to develop unchecked, trees may be killed. Ter- 

 minal twigs chacteri sti cal ly die first. The fruits of infested 

 trees often are mottled or spotted in appearance due to the red- 

 dish inflamed areas surrounding each of the scales. 



Life Cycle 



ti on 

 other 

 The s 

 to fl 

 bl oom 

 becom 

 ing y 

 are k 

 bark 

 settl 

 throu 

 al ong 

 ing 

 mouth 

 the p 

 gener 

 pests 



The inse 

 under sm 



stages 

 mall sea 

 ow i n th 

 The w 

 e winged 

 oung whi 

 nown as 

 for a sh 

 ing down 

 gh the b 



with th 

 nly flat 

 parts . 

 rotecti V 

 ations o 

 , they a 



ct pass 

 all bla 

 of the 

 1 es bre 

 e s p r i n 

 i nged m 

 nor em 

 ch have 

 "crawl e 

 ort tim 

 , they 

 ark and 

 e i r old 

 tened y 

 As they 

 e scale 

 f seal e 

 re favo 



es the 

 ck sea 

 i nsect 

 ak dor 

 g. Th 

 ales e 

 erge f 



the a 

 rs" , a 

 e seek 

 i nsert 



being 



skin 

 el low 



grow , 

 s unde 



each 

 red by 



wi nter 

 les. U 



are ki 

 mancy a 

 ey usua 

 merge i 

 rom ben 

 ppearna 

 nd they 

 ing the 



thei r 



s u c k i n 

 they lo 

 sacks a 



they s 

 r which 

 year in 



hot , d 



1 n a 



nder 



lied 



t abo 



lly b 



n May 



eath 



ce of 



craw 



prop 



s lend 



g the 



se th 



ttach 



ecret 



they 



this 



ry we 



dorm 

 New E 

 duri n 

 ut th 

 ecome 

 . Th 

 the s 



yell 

 1 ove 

 er sp 

 er th 



sap. 

 ei r 1 

 ed to 

 e a w 



live 



area 

 ather 



ant, par 

 ngland c 

 g the wi 

 e time t 



f ul 1 -gr 

 e female 

 cale giv 

 ow mites 

 r the su 

 ot to se 

 read-1 i k 

 They s 

 egs and 



the tre 



axy subs 



There 



As wi 



tly grow 

 ondi tion 

 nter mon 

 he sap b 

 own by f 

 s which 

 e birth 



or lice 

 rface of 

 ttle dow 

 e mouth 

 oon molt 

 antennae 

 es only 

 tance wh 



are pro 

 th most 



n condi- 

 s, all 

 ths. 

 egi ns 

 ull 

 never 

 to liv- 

 These 



the 

 n. Upon 

 parts 



and 



, becom- 

 by their 

 i ch forms 

 bably 3 

 i nsect 



The insects are carried from orchard to orchard on the bodies 

 of birds and larger insects, but probably to a greater extent by 

 wind or air currents. In common with many scale insects, they al- 

 so often spread on contaminated nursery stock. 



Control Measures 



These insects are best controlled with 60 or 70 Second oil at 

 2 gals/100 during the half-inch green stage. In order to realize 

 satisfactory control, it is necessary to obtain a thorough coverage 



