54 



(1) Labrum upper lip. 



(2) Mandibles jaws. 



(3) Maxillae, and maxillary palpi. 



(4) Labium and labial palpi. 



2. Thorax. 



(a) Prothorax. 



(1) First pair of legs. 



(b) Mesothorax. 



(1) Second pair of legs. 

 (1) First pair of wings. 



(c) Metathorax. 



(1) Third pair of legs. 



(2) Second pair of wings. 

 Wing veins and cells. 



Legs coxa, trochanter, femur, tibia, tarsus, and claws. 



3. Abdomen. 



(a) Ears (in locust). 



(b) Spiracles breathing holes. 



(c) Ovipositors for depositing eggs. 



METAMORPHOSIS OF INSECTS. 



1. Delevolpment with Metamorphosis. 



(a) Stages egg, immature insect, adult. 



(b) Examples Thysanura. 



2. Incomplete Metamorphosis. 



(a) Stages egg, nymph (several stages), adult and imago. 



(b) Examples locust, cricket, dragon fly, damsel fly, May fly. 



3. Complete Metamorphosis. 



(a) Stages egg, larva, pupa, imago. 



(b) Examples moths, butterflies, bees, ants, beetles, flies. 



ECONOMIC RELATIONS OF INSECTS. 



1. Effects. 



1400,000,000.00 of the agricultural products of the United States are 

 annually destroyed by insects. The Codling-moth exacts a yearly 

 tax of |3,000,000.00 in one State. 



Many insects are injurious and many are very beneficial. 



2. Warfare against Insects. 



(a) Is the insect injurious? 



(b) How does the insect feed? 



(1) Mouth parts formed for sucking. 



(2) Mouth parts formed for biting. 



(c) How can it best be attacked and when? 



(d) Are mechanical or chemical means most effective? 



