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- 



3TS 809 



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



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 two or three to ten or mure 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. — To the 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 

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

 bugs (Pig. 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- 



parts are not built for such feeding nnd is it i^ impi 

 ticable to poison the juice of til ] I nit it i t r 1 

 fight such Insects with a de i 1 1 1 1 1 1 1 m 1 1 



Insect must be actually Jut ^ i I 



knowledge of these fundam ii il iD 



habits of Insects would h i\ ' i ' im. , 



money that have been wasted iii tiMii-r ti (heck t 

 ravages of sucking Insects with Pari', green and simi: 



parts fitted both for ; 



Beneficial Insects. - 

 staunch and true friemN : 

 bee, the many wild bei-. 

 the blossoms to get foo.l i 

 and honey for man, k;i\ 

 shape of tiny grains of 

 crop of fruit that otherw 

 tain. The honey-bee is ot 

 fruits, especially scrapes. 

 guilty, au.l.-an"ru1,,Al,:n: 



: and for biting 



itu ripe 

 proved 

 shown 



:>ly sip- 



cO^ 



1153. Mouth 



tha 



ping the juice 



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 thera 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. Pig. 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 now about a thousand dif- 

 ferent kinds of Insects that may 

 be classed as injurious in the United States and Canada. 

 Over 600 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 scientiiically 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. Man 

 i s continually e n - 

 croaching upon and 

 thereby disturbing 

 nature's primitive 

 domain and the equi- 

 librium 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 

 lioi.rs have been at- 



which IW' 



San Jose Scale. 



le mature winter scale; 

 iiiseft itself, with its 

 ve feedinti org.ans. 



