INJURIOUS AND BENEFICIAL INSECTS 



13 



pound of cyanide of potassium to 150 cubic feet of space and treat- 

 ing before the buds start in the spring. 



17 English oyster scale (A s p i d i o t u e o s t r e a e f o r m i s). 

 This resembles the San Jos^ scale in appearance, but has the nip- 

 ple a little to one side of the center, and like it infests fruit trees. 

 It occurs in many localities in this state and should be guarded 

 against as occasionally it is found in great numbers. 



Treatment: spray infested trees with a 20 fo crude petroleum 

 emulsion before the buds start or with kerosene emulsion or whale 

 oil soap solution when the young appear in June. Fumigate with 

 gae. 



18 Putnam's scale (Aspidiotus ancylus). Eesembles 

 the two preceding species, but is less injurious. It attacks various 

 trees. The young appear the latter part of June. 



Treatment: same as preceding. 



Greenish, black 



SMALL. FRUIT AND VINE INSECTS 



19 Currant worm (P t e r o n u s r i b e s i i). 

 dotted saw fly larvae feed- 

 ing on currant leaves in 

 May, the common currant 

 worm. The parent insect, 

 a small, brownish, black- 

 headed, four winged fly, 

 appears the latter part of 

 April, deposits eggs along 

 the veins on the under side 

 of the leaf. A second brood 

 of flies occurs the last of 

 May or in June. 



Treatment : spray with 

 hellebore or poison. 



20 Currant span worm (Diastictis ribearia). Yellow- 

 ish, black dotted span worms feeding on leaves in May and June. 

 These are true caterpillars, and are easily distinguished from the 

 preceding species by their " looping " habit when walking. The 



Fig. 13 Immature currant worms (after Saunders) 



