THE CHAFF SCALE OF THE ORANGE. 39 



In fall may be assumed to be approximately contemporaneous with those 

 of the Long Scale. They occur in March or April and in September or 

 October. These months are therefore the proper ones for treatment 

 with remedies. 



Habitat. The Chaff Scale infests by preference the trunk and larger 

 branches, and to these it generally confines itself until every portion of 

 their surface is thickly coated, and the young Bark-lice can no longer 

 find places to plant themselves. It is also frequently seen upon the fruity 

 occupying the pit-like depressions of the rind. This habit, combined 

 with its light color, renders it inconspicuous upon the fruit. Upon the 

 trunks of trees, also, its resemblance to the bark causes it to escape 

 notice, so that many persons whose groves are suffering from the at- 

 tacks of this scale are unaware of its presence. 



Food-plants and Origin. It has been found upon various plants grow- 

 ing near infested orange trees. Japonicas and similar thick-leaved 

 plants sometimes suffer severely from its attacks. It is not known to 

 infest any native wild plants, and is not found upon the Wild Orange, 

 except in the immediate vicinity of cultivated plantations. . It cannot, 

 therefore, be considered a native insect, nor is anything known with 

 certainty concerning its introduction. 



Professor Glover, in his report to the Commissioner of Patents 

 for the year 1855, mentions the introduction in that year of a Scale- 

 insect, which he says was imported into Jacksonville, Fla., on some 

 lemons sent from Bermuda. This Scale-insect has been stated to be 

 Mytilaxpis citricola. From the brief description given by Glover, it is 

 not possible to determine with certainty the species referred to, but the 

 small size and shape of the female and the white color of the male scales 

 agree closely with the species now under consideration, and render it 

 probable that the Chaff Scale, and not the Purple Scale, was the insect 

 in question. 



Parasites. In addition to many external enemies, a single Hyuae- 

 nopterous parasite attacks this scale, and is a very efficient destroyer of 

 the species. It is a larger insect than those found in the scales of My- 

 tilaspis, and its larva does not live within the body of the Coccid, as is 

 usual with these minute parasites, but originates from an egg deposited 

 beneath the scale and among the eggs of the Scale-insect, which is al- 

 ways of adult size when attacked. The grub of the parasite makes 

 room for itself as it grows by eating first the eggs of its host and then 

 her body. Sometimes, indeed, the eggs alone of the Coccid appear to 

 suffice for its support and the mother Bark-louse is not molested. 



The pupa of the parasite is formed under the scale, and although 

 without cocoon or coverings of its own, is surrounded by the dry skin 

 and egg-shells of the Bark-louse. x 



The fly issues through a round hole which it eats in the top of the 

 scale. 



