246 



ANNELIDA AND ARTHROPODA: 



cracks and crevices or under objects during the day; 

 often plant pests and harmful (Figure 14.23). 



ORDER PLECOPTERA (Sfoneflies) 



Diagnosis: medium size to over two inches long; 

 four wings membranous, held pleated and flat on 

 back when at rest; chewing mouth parts, but often 

 none in adults; nymphs in fresh water, often under 

 rocks; adults poor flyers; nymphs and adults often 

 herbivorous, sometimes insect predators, but some 

 adults are short-lived and never feed; nymphs widely 

 preyed upon by aquatic predators; nymphs desirable 

 as bait for fresh-water fishing (Figure 14.23). 



Figure 14.23 Dermaptera, Isoptera, Plecoptero, Embioptera, Cor- 

 rodentio and Mallophogo: 1, Dermaptera, on earwig (to about 1 inch 

 long); 2, Isoptera, termites (large specimens; a, supplementary queen; 

 b, king; c, worker; d, soldier); 3, Plecoptero, stone flies (adult to the left 

 and aquatic nymph to the right, x 2); 4, Embioptera, a web spinner 

 (x 3'j);5, Corrodentio, a book louse (x 7); 6, Mallophogo, a biting 

 louse ( X 3). (After various sources.) 



ORDER ISOPTERA (Termites or "Whife Ants") 



Diagnosis: small to medium size; body soft, gen- 

 erally white or whitish; reproductive castes with four 

 similar, narrow wings, chewing mouth parts; social 

 insects (also ants, wasps, and bees) characterized by 

 a caste system; four castes, reproductwes (kings and 

 queens) have fully developed wings (shed after mat- 

 ing), compound eyes, and usually pigmentation; sup- 

 plementary reproductwes also reproduce but have shorter 

 wings, usually smaller eyes, and less pigmentation 

 than reproductives; workers which are sterile males 

 and females and nymphs are wingless, usually lack 

 compound eyes, and are pale in color; soldiers are 

 sterile males and females with greatly enlarged heads 

 and mouth parts; sometimes there are two additional 

 castes, adults, which are similar to workers in appear- 

 ance but can reproduce, and nasuti, which are sterile 

 adults with a narrow snout that is used to squirt a 

 sticky secretion at an intruder; some termites have 

 only two castes, reproductives and workers; herbivo- 

 rous, well known for their destruction of wood; can 

 use wood cellulose because cellulose-digesting proto- 

 zoans are present in termite digestive tracts (Figure 

 14.23). 



ORDER EMBIOPTERA (Web-spinners) 



Diagnosis: small (1/6 to 1/3 inch), elongate, soft 

 but straight-sided; rarely encountered; females wing- 

 less, males usually winged; chewing mouth parts; 

 mostly colonial forms living in runways in debris, 

 cracks, under bark, or among plants; runways are 

 lined with silk; feed mainly on dead plant remains 

 (Figure 14.23). 



ORDER CORRODENTIA (Book Lice) 



Diagnosis: minute to small, to about 1/4 inch 

 long; four membranous wings or none; chewing 

 mouth parts; most frequently encountered in human 

 dwellings, often in books or papers; indoor forms 

 wingless; most are winged and live on trees or shrubs 

 or under bark or stones and feed on molds, fungi, 

 pollen, cereals, and dead organisms (Figure 14.23). 



ORDER MALLOPHAGA (Biting Lice) 



Diagnosis: small to minute, to about 1/4 inch 

 long; wingless; chewing mouth parts; external para- 



