2 MAINE AGRICULTURAL EXPERIMENT STATION. 



are as apt to capture the beneficial and the harmless as the 

 injurious. Poisons, traps, and other repressive measures must 

 be used with caution, and at the right time and place in order 

 to be most effective. 



Though technical terms will be avoided in this circular when 

 possible, it may not be out of place here to explain the few 

 which it will be necessary to use in the descriptive matter which 

 is to follow. 



Though differing in many particulars all insects possess a 

 segmented body which in the adult stage is arranged in three 

 regions, head, thorax or midbody, and abdomen or hind body. 

 The thorax in the adult is provided with 3 pairs of legs and may 

 be either winged or wingless. 



Some insects (e. g, grasshopper) after emerging from the 

 egg gradually increase in size until they reach maturity but 

 without undergoing any abrupt change in external appearance 

 except in the acquisition of wings. Others, however, pass 

 through 4 distinct stages, viz., egg, larva (caterpillar, or grub 

 or maggot), chrysalis or pupa (often enclosed in a cocoon) 

 and the imago or mature insect. After the insect has acquired 

 wings it is mature and no longer increases in size. Thus a small 

 beetle is not the young of a larger one, nor is a small fly the 

 early stage of one of greater magnitude. 



Insects are divided into a number of natural groups or orders 

 by which they are known in technical literature and not infre- 

 quently in popular accounts also. The Orthoptera are four 

 winged ; the first pair are thickened and partly overlap when at 

 rest ; the second pair are thinner and are folded in plaits like 

 a fan. The mouth parts are formed for biting. To this order 

 belong the cockroaches, crickets and grasshoppers. The Neu- 

 ropteroids include the dragon flies (popularly known as darn- 

 ing needles), May flies, stone flies and the like. The only 

 insects which are rightly called "bugs" are the Hemiptera, crea- 

 tures of various shapes, having jointed beaks adapted for pierc- 

 ing and sucking. Plantlice (figs. 31, 32), scale insects (figs. 

 3, 4), bed buds, plant bugs (fig. 28), etc., belong to this order. 

 The butterflies and moths, scaly winged insects, are classed as 

 Lepidoptera. These are harmless to vegetation in the adult 

 stage, but many species in the larval (caterpillar) stage, then 

 provided with biting mouth parts, are among our most destruc- 



