HOW SAN JOSE MAY BE DISTINGUISHED FROM THE ABOVE SCALES. 



If it is not advisable to try to show how the above four scales may be distin- 

 guished from one another, it is very important to give simple methods by which any 

 person can tell if he finds one of these whether it is the San Jose Scale or not. The 

 following points will enable him to do so: 



(1) All five scales, if the surface is rubbed, will show a small nearly circular 

 area quite different in color from the rest of the scale. This area we shall call the 

 exuviae, because it is due to the moulted skins (exuviae) of the insect having 

 become 'worked into the covering scale and showing through it. In the San Jose 

 scale the exuviae is situated in, or almost in, the centre of the scale, and is yellowish. 

 In most of the other four scales it is situated a little to one side of the centre, and 

 is either some shade of red or orange, being very rarely yellowish. Frequently it 

 is covered over by a film which conceals it unless first rubbed gently. The color and 

 position of the exuviae are therefore very helpful distinguishing characteristics. 



(2) Among the adult males and females of the San Jose Scale are always to be 

 found a very large percentage of small black scales, each with a little nipple in the 

 centre and groove around it. This has been already described, and mentioned as 

 being also the wintering stage of this scale. If none of these small black scales are 

 to be' found the insects are not San Jose, or if some are present that, roughly speak- 

 ing, answer to this description but are not black they are not San Jose. 



(3> Look for the adult female scales, and if these though circular are more 

 than 2 mm. about 1-12 of an inch) in diameter the scale is not San Jose, because 

 the adult female of this is never more than 2 mm., and is usually about 1.5 mm. 

 or 1-16 of an inch in diameter, whereas the adult female of the English Walnut 

 Scale {Aspidiotus juglans-regiae) is 3 mm., or nearly ji of an inch in diameter. 

 The other three species are smaller than it, and nearer the size of San Jose. 



(4) If the scale occurs in abundance on the fruit and causes red spots on it, or 

 if it often produces a reddish discoloration on young shoots, or if, when the bark of 

 a badly infested branch is cut through obliquely, the tissues beneath are seen to be 

 stained purple or reddish, the insect is almost certain to be San Jose Scale. It is 

 true that the Curtis Scale and also the Scurfy Scale will produce red spots on the 

 fruit, but they are very seldom found on it. Moreover the Scurfy Scale is not 

 circular and does not resemble the San Jose closely. 



These points, along with a careful study of the description given above and of 

 the accompanying illustrations, should make the identification of San Jose Scale 

 comparatively easy. 



A Eed Spotting of Fruit not Caused by San Jose Scale. — Frequently one 

 sees various kinds of apples in autumn with tiny red spots on the sujface. Bell- 

 flowers are very subject to this. At first glance these spots are very suggestive of 

 San Jose Scale, but on a close examination with a magnifying glass it is easy to 

 discover that they are due to some other cause, probably some species of fungus. 

 If they had been caused by any scale insect either this would be present and could 

 be lifted up with the point of a knife blade or with a pin or it would leave a light- 

 colored central area showing that it had been removed by something. The spots 

 referred to above, however, are darkest in the centre, and in this darkest part the 

 epidermis is usually ruptured as if by a fungus growth. 



