6 INSECTS INJURIOUS TO VFX.ETABLKS 



old Linnsean classification will sufiice. This embraces seven 

 orders, — Coleoptera, Orthoptera, Lepidoptera, Hymenoptera, 

 Neuroptera, Diptera, and Hemiptcra. The first six of these 

 orders are mandibulate or chezving insects, at least in the most 

 active stage of the insect, while the last are haustellate or 

 sucking insects. This is important to know as on this classifica- 

 tion depends the question as to whether stomach poisons, such 

 as the arsenicals, or contact poisons, such as kerosene and its 

 different preparations, are best suited for their destruction. 



ORDERS OF INSECTS 



Coleoptera or Beetles. — Beetles are distinguished by having 

 a pair of more or less horny elytra or wing-covers which nor- 



Fig. 8.— Convergent \adyh\rd (Hippodamia conuefgens). a Adult: Z?. pupa, 

 c, larva. All much enlarged. (Author s illustration, U. S Dept Agr ) 



mally meet in a straight line down the back. Beneath them 

 are the true membranous wings, usually folded. The mouth- 

 parts of beetles and their larvae (the latter usually called 

 grubs) are formed for biting. A common beetle, a beneficial 

 ladybird, is shown in figure 8, in different stages. Many species 

 of beetles are injurious both in the adult and larval stages 

 Among the best known forms of this order that injuriously 



