114 



AiV ECONOMIC EXTOMOLOGY. 



if soapsuds be used to dilute the emulsion, instead of water, the 

 cottony mass will be so impregnated with soap, and become so 

 compact, that the young will be unable to make their way out. 

 Therefore, in this case, dilute three quarts of kerosene emulsion 

 with one pound of whale-oil soap dissolved in eight gallons of 

 water. 



The most troublesome of all scale insects belong to the Dia- 

 spincB^ or "armored scales," and these are generally small in 

 size. They are, as a rule, only a little convex, occasionally even 

 flattened, and in texture are more like membrane or parchment 

 than wax. All kinds of shapes occur, and there is considerable 

 variation in life history. In one point they all agree, — after the 

 active larvae have once become fixed and covered with a scale, 

 they never leave their position, except when the males emerge 

 as adults and visit the surrounding females. In general the life 

 history of the insects is as follows : the larvae, whether hatched 

 from the eggs or born alive, crawd about for a fe\v hours, or at 

 most a day or two, seeking a convenient place to fix. • They are 

 always minute, flattened, oval creatures, with six legs, a pair of 

 distinct feelers, and a curious, long, sucking mouth. This is 

 soon inserted into the plant tissue, and from that time the insect 

 is a fixture. Little waxy filaments begin to exude from the body, 

 w^hich soon coalesce, or run together, forming a first covering or 

 scale over the soft larva. The insect soon moults, and the cast 

 skin forms part of the scale, the resulting creature being legless 

 and without power of motion. There is one additional moult, 

 after which the sexes are very diflerent in appearance. The male 

 shows antenna, legs, and wings well marked, and is indeed a 

 perfect pupa, while the female is even more grub-like than before, 

 rudiments of antennae only being visible. The second cast skin 

 of the female also forms a part of her scale, and there is nearly 

 always some difference in shape between the sexes, the male 

 being not only smaller, but narrower. Shortly after the change 

 to the pupa the male becomes adult, and in this series has the 

 end of the abdomen prolonged into a style or pointed process, 

 sometimes equalling in length the rest of the insect, though 

 usually shorter. Antennae and wings are both prominent, and 

 as a whole the insect is curious and exceedingly fragile in appear- 

 ance. Its life is probably short, though long enough to accom- 



