LESSONS IN ZOOLOGY. 281 



eating and many of them familiar insects, well worthy of study 

 and investigation. 



The Neuroptera, includes insects that have biting mouth parts, 

 membranous wings, and that pass through a complete meta- 

 morphosis. They have something the appearance of the dragon 

 flies and May flies. One member of this order has long horns 

 and long delicate wings, and is called the Horned corydalis. 



The Strepsiptera includes a few insects of minute size and no 

 special interest. 



The Rhynchota are insects that have piercing mouth parts, 

 and pass through an incomplete metamorphosis. The Pediculidse 

 and other animal parasites, theAphida? and other plant-lice, and 

 the Cicadidse belong to this order, and so do the Hemiptera or 

 bugs, water bugs, etc. The bugs may be known by their anterior 

 wings which are horny toward the base and membranous toward 

 the tip. The Coccus cacti oi Mexico yields a coloring matter called 

 cochineal, which has considerable commercial value. 



The Diptera. The members of this order are insects with 

 piercing and sucking mouth parts, passing a complete metamor- 

 phosis. The posterior wings are reduced to mere knobs, so that 

 they appear to have but one pair. This group includes insects 

 that are parasites on animals, and sometimes on other insects. 

 The common house fly, the bot fly, gad flies, gnats, fleas, mos- 

 quitoes and others are members of this order. 



The Lepidoptera are insects having suctorial mouth parts, 

 two pairs of wings similar in form, which are covered with deli- 

 cate scales. This group includes the moths with feathery an- 

 tennae, that are active at night, and the butterflies with knobbed 

 antennae that are active during the day. Both moths and but- 

 terflies are noted for their beautiful colors and graceful forms. 

 They pass through a complete metamorphosis, and the cocoons 

 spun by some of the larvae of this group are the source of the 

 silk of commerce, making the silkworm chief among insects for 

 the economic value of its work. 



The Coleoptera are insects with masticating mouth parts, and 

 hardened anterior wings, which are the chief 'characteristic of 



