432 STATE BOARD OF AGRICULTURE. 



DESTRUCTIVE LARVJi:. 



Most insects, like the one just referred to, are only destructive while in 

 tlie worm-like or hirval stage. Thus the maggot of the Hessian fly or wheat 

 midge is what robs the farmers' pockets often to the tune of millions. It is 

 the caterpillars, not the moths, which as cut-worms sometimes destroy whole 

 fields of growing corn. It is the white grub, not the May beetle, that causes 

 the grass and corn to wither often for acres in extent. The wireworm or grub, 

 not the parent sna})ping-beetle, is what blights the grain fields. The caterpil- 

 lars known as army worms, not the graceful moths which only lay the eggs, 

 are what devastate the oatfields, sometimes throughout entire neighborhoods, 

 counties or even States. The same truth is illustrated in the orchard. The 

 canker-worm, the tent caterpillar, the apple worm, the borers, the slugs are 

 all larvffi of insects which in maturity would be entirely harmless, except 

 that they laid the eggs, which hatched and thus gave rise to the terribly 

 destructive larvte. 



DESTRUCTIVE IMAGO. 



On the other hand, a few insects, like the destructive rose chafer, and the 

 small but ravenous striped cucumber-beetle arc most troublesome, often only 

 destructive, when in the mature state. Other insects, like the Colorado potato 

 beetle, which has worked such ruin in its devastating march across our country, 

 and the bugs and locusts, are not content to feast and destroy only while in 

 the larval stage, but continue their voracious habits, even to their death. 

 Some of these insects, as illustrated in the western locust or grasshopper, do 

 their very worst damage when in the mature state. 



CLASSIFICATION OF INSECTS AS TO STRUCTURE OF MOUTH-PARTS. 



Insects are haustellatc, that is, provided with a beak or sucking tube; or 

 mandibidate, in which case they have jaws which move sidewise and with which 

 they grasp, cut or nip off their food. The haustellate group includes all 

 mature insects of the hpidoptera — the butterflies and moths — and the dijitera, 

 or two-Avinged flies. If we except tiie biting flies, — it were more proper to say 

 the piercing or stabbing flies, — like the mosquito, the gnat, the horse-flies and 

 gad-flies, none of the above do damage while in the mature state. The bugs, 

 too, which include plant lice, bark lice, bedbugs, most parasitic lice, and such 

 arch destroyers as the squash bugs and chinch bugs, are throughout their 

 entire lives haustellate. Such insects must, of course, pierce through the 

 exterior and suck out the circulating sap or blood which serves them for nour- 

 ishment ; and could not be killed by applying poisons to the surface of their 

 food. Therefore s[)rinkling plants with Paris green, hoping to kill the devas- 

 tating plant lice or squash bugs, would be vain and fruitless. 



To the second group — mandibulate insects, — belong all larval insects, that 

 liave their moutii-parts developed, if we except the larval bugs just referred 

 to above, and all mature insects, with the exception of the moths, butterflies, 

 two-winged flies and bugs. Such insects bite off and eat their food, much as 

 the rabbit and woodcliuck nip off and munch the bits of cabbage leaf. It 

 is easily to be seen, then, that poison, dusted or sprinkled on the plants which 

 are attacked, would of necessity be taken with the food and furnish a capital 

 remedy. 



A few insects like the Uessian fly, maggot, and the maggot of the onion, 

 cabbage and radish flies have no mouths at all, and can only take their food 

 by absor])tion. 



