12 



THE APPLE BARK LOUSE, OR OYSTER SHELL SCALE (Figure No. 4.) 



Aspidioius Conchiformis (Gmelin). 

 Mytalaspis Pomicorticis (Riley). 



Figure Xo. 4. 



This is one of the few insects which the Northeastern States have in 

 common with us. Like the preceding one, it has only one brood during the 

 season. It affects the apple chiefly, although sometimes the pear, also. It 

 is confined chiefly to the coast counties, but is also found in other places, 

 as San Joaquin Valley. Owing to the thickness of the armor, it is one of 

 the most difficult of the scales to exterminate. 



Description of Figure Xo. 4: 1. Egg; 2. Young insect (larva) ; 3. Appear- 

 ance of secretion as it hardens and forms shell over body of insect; 4. A 

 form of the scale before it reaches maturity; 5 and 6. Appearance of insect 

 after casting skin, limbs, and other appendages; 7. Scales (cover) at ma- 

 turity; 8. Antennae. All of these figures highly magnified. Description 

 of insect, etc.: Eggs, number under each scale, thirty to seventy-five; 

 length, one one hundredth of an inch; form, irregularly ovoid; color, snow 

 white, when near hatching, yellowish. Larva: Length of body, one one 

 hundredth of an inch; form, ovoid, three times as long as wide: color, pale 

 yellow. Antennae, sometimes six-jointed, but generally seven-jointed. Anal 

 setse, two, about two thirds as long as body. Male insect (perfect) : Length, 

 one forty-fifth of an inch; color, flesh-colored gray; abdomen and thorax, 

 about same length as seen from above; wings, nearly transparent. "The 

 last joint of abdomen narrowed into a large tubercle bearing four bristles 

 on the under side, and sending forth the genital armor in the form of an 

 awl-shaped stylet as long as abdomen." 



Remedies. — For a number of years I have tried to find an effective remedy 

 against this scale. I have tried concentrated lye, one pound to the gallon, 

 with the effect of damaging the trees. Finally, one half pound of lye and 

 one half pound commercial potash to one gallon water was used last winter, 

 and applied to the orchards on the experimental grounds of the University. 

 The success was very marked. No damage was done to any but a few trees 

 that had started prematurely. With various summer washes on this scale, 

 I accomplished but little good. 



