INSECTS 



INSECTS 



809 



ter. The old skin is shed in its entirety, even from 

 all the appendages, and sometimes remains in such 

 a natural position where the Insect left it as to easily 

 deceive one into thinking that he is looking at the In- 



1151. Ground beetle. 

 One of the commonest pred:iceous insects. 



sect rather than at its cast-off clothes. Some Insects are 

 so neat and economical that they devour their old suits 

 or skins soon after moulting them. Larvae, or nymphs, 

 may moult from twq or three to ten or more times ; the 

 larvae do not often change strikingly in appearance, but 

 the nymphs gradually acquire the characters and struc- 

 tures of the adult. 



How They Eat. — Tothe horticulturist, the mouth-parts 

 of an Insect are its most important organs or appen- 

 dages. The mouth-parts are built on two very differ- 

 ent plans. Grasshoppers, beetles, caterpillars and grubs 

 have two pairs of horny jaws, working from side to 

 side, with which they bite or chew off pieces of their 

 food, that then pass into the food-canal for digestion 

 (Fig. 1153). The scale Insects (Pig. 1154), plant-lice, true 

 bugs (Fig. 1155), mosquitoes and others have these jaws 

 drawn out into thread-like organs, which are worked 

 along a groove in a stiff beak or extended under lip. 

 Such Insects can eat only liquid food, which they suck 

 with their beak-like mouth-parts. The Insect places its 

 beak on the surface of the plant, forces the thread-like 

 jaws into the tissues, and then begins a sucking opera- 

 tion, which draws the juices of the plant up along the 

 jaws and the groove in the beak into the food-canal of 

 the Insect. 



Thus a sucking Insect could not partake of particles 

 of poison sprayed on the surface of a plant. Its mouth- 



=^ 



'^S^it 



U52. Moths of the peach-tree borer. 

 The lowest one is male. 



parts are not built for such feeding, and as it is imprac- 

 ticable to poison the juice of the plant, one is forced to 

 tight such Insects with a deadly gas, or each individual 

 Insect must be actually hit with some insecticide. A 

 knowledge of these fundamental facts about the eating 

 habits of Insects would have saved rauch time and 

 money that have been wasted in trying to check the 

 ravages of sucking Insects with Paris green and similar 

 poisons. 



1153. 



Some Insects, like the bees and wasps, have mouth- 

 parts fitted both for sucking or lapping and for biting. 

 Beneficial Insects. — The horticulturist has many 

 staunch and true friends amongthe Insects. The honey- 

 bee, the many wild bees, and other Insects, as they visit 

 the blossoms to get food for themselves, for their young, 

 and honey for man, leave an insurance policy in the 

 shape of tiny grains of pollen, which often insures a 

 crop of fruit that otherwise might be extremely uncer- 

 tain. The honey-bee is often accused of biting into ripe 

 fruits, especially grapes. They have not yet been proved 

 guilty, and careful, exhaustive experiments have shown 

 that they will not do it under the most favorable circum- 

 stances. Wasps and other strong-jawed Insects are re- 

 sponsible for most of this injury, the bees simply sip- 

 ping the juice from the wound. 



Most of the pretty little beetles known to every child 

 as "lady-bugs" eat nothing but injurious Insects; many 

 other beetles are also predaceous. Man is also often 

 deeply indebted to many of the two- winged Insects or 

 true flies whose larvEe live as parasites inside the body of 

 Insect pests or feed upon them predaceously. Were it 

 not for the ravenous larvae of the "lady-bugs" and of 

 the syrphus flies, plant-lice of all kinds would soon get 

 beyond control. While man must recognize these little 

 friends as valuable aids in his warfare against the 

 hordes of Insect pests, it will 

 rarely be safe to wait for the 

 pests to be controlled by their 

 enemies. Fig. 1156 shows a 

 tomato worm bearing the co- 

 coons of a parasite. Fig. 1151 

 shows one of the predaceous 

 beetles destroying a cutworm. 



Injurious Insects. — There 

 are uow about ;i thousand dif- 



" " ferent kiu<lsof Insects that may 



be classed as injurious in the United States and Canada. 

 Over tiUO kinds were exhibited at the Columbian Expo- 

 sition in 1893. All of these may not be injurious every 

 year, as most Insect pests have periods of subsidence, 

 when certain factors, possibly their enemies or perhaps 

 climate conditions, hold them in check. The outlook 

 for American horticulturists, so far as injurious Insects 

 are concerned, is not encouraging. Nowhere else in the 

 world are Insects being fought as intelligently, success- 

 fully and scientifically as in America, yet we never have 

 exterminated, and it is very doubtful if we ever will, a 

 single Insect pest. This means that American horticul- 

 turists will never have any fewer kinds of Insects to 

 fight. On the contrary, there are many more Insect 

 pests now than in our grandfather's early days, and new 

 pests are appearing every year. This alarming state of 

 affairs is largely due 

 to two causes, for 

 both of which man 

 is- responsible. Min 

 i s continually e n 

 croaching upon and 

 thereby disturbing 

 n ature's primitive 

 domain and the equi 

 librium which li 

 there become est 1 

 lished between ii i 

 mals and plants In 

 consequence, Insects 

 like the Colorado po 

 tato beetle, the apple 

 tree or the peach tree 

 borers have been at 

 tracted from their 

 original wild food 

 pbmts to man's culti 

 vated crops, which 

 often offer practically 

 unlimited feeding 

 grounds. Most of the 

 new Insect pests, 

 however, are now 

 coming to America 

 from foreign shores. 

 American horticul- 



1154. San Jose Scale 



Showing the mature winter scale; 



