INSECTS 



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

 all the appendages, and sometimes remains in such 

 a natural position where the Inseet left it as to easily 

 deceive one into thirdtin^ that he is looking at the In- 



INWECTS 



809 



1151. Ground beetle. 

 One of the commonest predaceous insects. 



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

 so neat and economical that they devour their old suitw 

 or skins soon after luoultinf^ them. Larvte, or nymphs, 

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

 larvae do not often change strik:iny:ly in appearance, but 

 the nymphs gradually acquire the characters and struc- 

 tures of the adult. 



How Theij £<Vt^. — To the horticulturist, the mouth-parts 

 of an Insect are its most important organs or appen- 

 dages. The mouth-parts arc 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 (Fig. 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 fuod-canal of 

 the Insect. 



Thus a sucking Insect could not partake of particles 

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



1152. 



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 

 fight 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 much time and 

 money that have been wasted in trying to check the 

 ravages of sucking Insects with Paris green and similar 

 poisons. 



1153. Mouth-parts of a 

 biting insect. 



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

 parts fitted both for suckiTig or lapping and for biting. 

 Beneficial Insects. — The horticulturist has many 

 staunch and true friends amongtbe Insects. The honey- 

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

 the blossoms to get food f<»rthumselves, 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 e.xtremely uncer- 

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

 fruits, especially grapes. They have not yet been proved 

 guilty, and careful, exhaustive experiments have shown 

 that they will not do ituuder the most favorable circum- 

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

 spimsible for must 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 Hies whose larvse live as parasites inside the body of 

 Insect pests or feed upon them preduceonsly. Were it 

 not for the ravenous larvae of tbe "lady-hugs" 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 tbe 

 pests to be controlled l)y their 

 enemies. Fig. ] 156 shows a 

 t(miato worm bearing the co- 

 <-oons of a parasite. Fig. 1151 

 shows one of the predaceous 

 bi-etles destroying a cutworm. 



In.turious Insects. — There 

 are now about a thousand dif- 

 ferent kinds of Insects that may 

 be classed as injurious in the United States and Canada. 

 Over OUO kinds were exhibited at the Columbian Expo- 

 sition in 1893. All of the^e may not be injurious every 

 year, as most Insect pests have periods of subsidence, 

 when certain fa^-tors, possibly their enemies or perhaps 

 climate conditinns, Imjil tljcni 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 donbtful if we ever will, n 

 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. Man 

 1 s continually e n - 

 croaching upon and 

 thereby disturbing 

 n ature's primitive 

 domain and the equi- 

 libritim which has 

 there become estab- 

 lished between ani- 

 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- 

 ])lants to man's culti- 

 vated crops, which 

 often offer priictically 

 unlimited feeding 

 grounds. Most of the 

 new Insect ])ests, 

 however, are now 1154, San Jose Scale, 



coming to America showing the mature winter scafe; 

 from foreign shores. ,^\^c, the insect itself, with its 



.\nierican borticnl- thread-like feeding organs. 



