ENTOMOLOGY 125 



at once. A better method, perhaps, is to first dissolve the sulphur 

 with lye, as follows: 



Mix 20 pounds of flowers of sulphur into a paste with cold 

 water, then add 10 pounds of pulverized caustic soda (98 per cent). 

 The dissolving lye will boil and liquefy the sulphur. Water must 

 be added from time to time to prevent burning, until a concentrated 

 solution of 20 gallons is obtained. Two gallons of this is sufficient 

 for 50 gallons of spray, giving a strength of 2 pounds of sulphur and 

 1 of lye to 50 gallons of water. An even stronger application can 

 be made without danger to the foliage. This mixture can also be 

 used in combination with other insecticides. 



There are several species of mites which attack citrus plants, 

 the most troublesome one of which, especially in Florida, is the 

 one named above. Almost any insecticide will kill the adult mite, 

 such as kerosene emulsion, resin wash, or even a simple soap wash, 

 but unless the eggs are killed the trees will be reinvaded about as 

 thickly as ever in the course of a week or ten days. The advantage 

 of the sulphur treatment arises from the fact that the sulphur ad- 

 heres to the leaves and the young mites are killed as soon as they 

 come in contact with it. 



The Six-Spotted Mite. This leaf mite or spider, is closely 

 allied to the common red spider of greenhouses. It first made its 

 appearance as an important orange pest in Florida in 1886. Fol- 

 lowing the severe freeze of the winter of 1885-86, the weakened 

 trees seemed to be especially favorable for the multiplication of 

 this mite; it increased suddenly in enormous numbers during the 

 dry weather of the early summer and was responsible for very con- 

 siderable damage to the foliage of the orange. The original food 

 plant of this mite is unknown. It was first noted on wild orange, 

 from which it spread to other citrus trees. It is probably a native 

 of Florida. 



Like its allies, this insect is greatly influenced by climatic con- 

 ditions, and needs for its excessive multiplication dry hot weather. 

 Therefore, in rainy seasons it is not especially troublesome, and 

 it usually disappears as soon as rainy weather sets in. In Florida 

 its period of greatest destructiveness falls between February and the 

 middle of May. This mite was carried to California a decade or 

 more ago with Florida stock, doubtless at the same time that sev- 

 eral other Florida citrus insects were transported to the Pacific 

 coast. In California, however, the principal mite injury seems to 

 be due to an allied species, also brought from Florida. 



The attacks of the six-spotted mite are confined largely to the 

 under sides of the leaves, which are covered with a fine web, be- 

 neath which the mite feeds. The first indication of its presence 

 is usually a yellowing in streaks and spots of the upper surface of 

 the leaves. The under surface becomes soiled by the accumulated 

 excrements in the form of minute black spots and by the web of 

 the mite. On badly attacked trees the foliage curls and plirivol.s 

 and the trees may lo.se half or more of their loaves, and similarly 

 also a large percentage of the half-formed fruit. Being an ac- 



