INJURIOUS INSECTS. 



CHAPTER I. 



INSECTS SUCKING THE SAP OF PLANTS. 



Aphideans — General mode of reproduction — Pluni aphis — Honey dew— Woolly aphis — 

 Remedies for the root form — Gas lime — Remedies for the branch form — Rosin solutions- 

 Resistant stock — Scale insects — Classification of the coccidaj — Pernicious scale — Habits of 

 pernicious scale — Aspidiotus rapax — Rose scale — Scale insects affecting citrus trees — Aspi- 

 (liotus nerii — Lecanium oleas — Remedies — Parasites — -Lecanium hemisphericum — Tlie 

 brown apricot scale — Icerya purchasi — Rate of growth of icerya in different stages— Hab- 

 its of icerya — Natural enemies — Banding of trunk — Gas remedies — Modes of treatment — 

 The process — Doses of gas according to size of trees— Dry gas — The titus fumigator — Cost 

 of treatment — Mealy bugs. 



APHIDEANS. 



The insects of this family, hke the scale insects, belong to the Order Hem- 

 iptera. They take their nourishment direct from the trees, by inserting 

 their beaks into the bark. INIost of them work only on the soft, tender, and 

 sappy shoots, although some, as the woolly aphis, find attachment on the 

 wounds of older growth, as well as on the roots. These insects are remark- 

 able for their powers of multiplication and extraordinary quickness of 

 development, and some scientists have calculated that a single aphis may 

 in five generations be the progenitor of nearly six millions of descendants — 

 a statement any one watching their increase in twenty-four hours on a 

 plum tree will hardly doubt. 



Latrielle, a French naturalist, claims that an average aphis produces 

 twenty-five young in a day; but Mr. Buckton, an authority on aphidse, 

 says that the highest number he has seen produced is eight, but as these 

 are ready to increase in five days, it will be seen that the rate of increase 

 is prodigious, and were it not for the natural checks, especially of certain 

 insects — syrphus flies and ladybugs, in particular (see chapter on these 

 insects) — they would literally fill the earth. 



GENERAL MODE OF REPRODUCTION. 



In regard to this, Mr. Buckton says: 



The extreme variety of the males of some living forms, such as the Entomostroca', would 

 seem to prove little more than that the influence of the male element sometimes is exerted 

 at a minimum. That the male, in such cases, is not wholly absent might even show how 

 necessary is the conjunction of primordial cells to perpetuate every species, though such 

 a union may be deferred to very long periods. It maj^ be pretty safely asserted that all 

 originallj' proceed from impregnated ova, and at the end of their generations they again 

 produce ova. We are in better position to state this, now that the true sexes of twelve, 

 or more, species are known, and have been satisfactorily made out bv dissection. 



The egg-laying process happens at different seasons of the year according 

 to the different genera. With very few exceptions, the egg-laying female 

 oviposits late in autumn and dies. The male generally appears before the 

 female. The egg when newly laid is commonly yellow, but changes into 

 shining black or brown. They are usually found at the base of the twigs 

 and are fastened by a gluey substance. The eggs of the aphis are very 



