io6 AN ECONOMIC ENTOMOLOGY. 



heavy oil or grease should be applied thoroughly. It will add 

 to the effect of the mixture if a little carboHc acid is added, but 

 it is not essential, though desirable to prevent rancidity if animal 

 fat is used. The kerosene emulsion, used with a brush or curry- 

 comb in cleaning animals, is also effective ; in fact, the treatment 

 suggested for the biting lice is also applicable here. 



The section Homoptera contains scale-insects, bark-lice, mealy 

 bugs, plant-lice, tree-hoppers, leaf-hoppers, frog-hoppers, and 

 others whose very names proclaim their character. Nowhere do 

 we find predaceous forms, or such as can be accounted beneficial 

 to the agriculturist. To be sure, we have among the Coccids the 

 cochineal and lac insects, but these are fully as injurious as any 

 other to plant life, and are useful simply because man is able to 

 make better use of them than of the plants upon which they feed. 



The family Coccidcs includes scale-insects and mealy bugs, cu- 

 rious in their life history as well as injurious to cultivated plants. 

 The males, unlike other Hemiptera, have a complete metamor- 

 phosis and only a single pair of wings, the secondaries disap- 

 pearing or reduced to mere hooks. They are singular, fur- 

 thermore, in that the mouth parts are replaced in the adult stage 

 by a pair of eyes. The female is always wingless throughout her 

 entire life, generally grub-like and stationary, covered with some 

 sort of waxy scale or by a powdery or cottony secretion. 



Mealy bugs derive their name from the fact that they are cov- 

 ered by a white, powdery substance, which is really a granulated 

 wax and a secretion of the insects themselves. They move about 

 freely, and are furnished with all sorts of odd processes at the 

 sides of the body, or with long filaments at the end. They are 

 not usually common in the North except in greenhouses and on 

 in-door plants, but become more abundant southward, where out- 

 door plants are also infested, orange-trees in Florida being par- 

 ticularly troubled. To this series of mealy bugs the cochineal 

 insect, Coccus cacti, belongs. It is a native of Mexico, but has 

 been cultivated in other countries, feeding upon species of cac- 

 tus. Specimens have been found in Florida, and it is more than 

 likely that it occurs not uncommonly in the semitropical part of 

 the peninsula. It also occurs in California. The dye is simply 

 the immature female insect, which is brushed off the plants, 

 killed, and dried, and has never been equalled for brilliancy and 



