21 



Usinger: Introduction 



Classification of Coastal Waters Inhabited by Insects 



Estuaries and open water bays. Salt or brackish 

 waters. San Francisco Bay, Carquinez Straits. 

 Trichocorixa reticulata (Guerin) in shallower pools 

 including brine pools (Leslie Salt Co.). 

 Intertidal rocks. Exposed to the full force of the 

 waves and to tidal fluctuations. Clunionino midges 

 (Chironomidae) with wings often reduced or absent. 

 A crane fly (Dicranomyia). Beetles of the genera 

 Liparocephalus (Staphylinidae); Ochthebius (Hy- 

 draenidae); Thalassotrechus (Carabidae); and Eury- 

 stethus (Eurystethidae). The larvae of flies and 

 larvae and adults of beetles feed on marine algae. 

 Adult beetles are found in cracks in the rocks at 

 low tide. Marine midges emerge, mate, and lay eggs 

 during the relatively brief periods when their hab- 

 itats are exposed by low tides. 



Beaches and mud flats. Exposed or partly protected 

 from the waves. Subjected to tidal fluctuation. 

 Aquatic insects scarce. Deinocerites mosquito 

 larvae in crab holes. Ephydra flies in salt pools. 

 Many essentially terrestrial insects in beach drift. 

 Tidal marshes. Usually protected from wave action. 

 Vegetation of marine algae, salt-marsh grasses 

 and Salicornia. Salt-marsh mosquitoes (Aedes dor- 

 salis and squamiger). Sand flies (Culicoides). 



C, 



D. 



Miscellaneous Aquatic Habitats 



Insects occur in a few unusual situations that deserve 

 special mention. 



Snow and ice. — A wingless Tipulid fly, Chionea 

 nivicola Doane, and the golden snow flea, Onychiurus 

 cocklei (Folson), are found on the surface of the snow 

 in the high Sierra. Eggs of the snow mosquitoes, 

 Aedes hexodontus, A. communis, remain beneath the 

 snow all winter and hatch as the snow melts in the 

 spring or early summer. The primitive orthopteran, 

 Grylloblatta, lives at the edges of glaciers and snow 

 fields in the high Sierra and in the ice caves of Modoc 

 County. It is not aquatic but is never found far from 

 snow or ice. 



Bogs. — Dense sphagnum grows in some parts of 

 California, either as a marginal shore line in bog 

 lakes or as a low dome-shaped carpet in a peat moor 

 (intro. fig. 25) or "hanging bog." The semiaquatic 

 shore bugs (Saldidae) are common under such circum- 

 stances, and the small insectivorous sundew plants 

 (Drosera) capture a variety of insects on their sticky 

 tentacles. Pitcher plants (Darling tonia) occur in some 

 bogs in the northern part of the state. Insects are 

 trapped in these, but no mosquito larvae (Wyeomyia) 

 have been found as in the Sarracenia pitcher plants 

 of the southeastern states. 



Tree holes. — This inconspicuous aquatic habitat 

 is often overlooked but is so common in deciduous 

 forests (Quercus, Vmbellularia) at middle elevations 

 in California that the principal insect inhabitant, 

 Aedes varipalpus (the tree-hole mosquito), is a major 

 pest. For reasons that are not entirely clear, water 

 in rotten limb holes and other parts of plants gives 



Intro, fig. 25. Diagrammatic cross section through o peot moor 

 that has arisen from a small lake (Ruttner, 1953). 



an acid reaction, is coffee-colored, and is high in 

 organic nitrogen. Under these conditions a unique 

 biota develops with several kinds of insects — a 

 crustacean, Cyclops, a small nematode, several types 

 of rotifers, and the protozoans Vortirella, Paramecium, 

 and Hypotrichia (Jenkins and Carpenter, 1946). In 

 California only Aedes varipalpus and several Holeid 

 larvae have been reported. 



APPLIED AQUATIC ENTOMOLOGY 



Man's conquest of the elements and progress toward 

 a civilized state is marked in part by his management 

 of water. Irrigation and pond-fish culture, seen in the 

 remains of prehistoric cultures, were early manifesta- 

 tions of this process. Modern man has perfected these 

 techniques and added measures for navigation, flood 

 control, hydroelectric power, sewage disposal, and 

 storage and transport of drinking water. To these have 

 been added such considerations as recreation and 

 improvement of the public health. It is doubtful if 

 any place in the world exceeds or even equals Cali- 

 fornia in extent of water management because of its 

 semiarid climate, intensive agriculture, and high 

 standard of living. Merely to describe the diverse 

 aspects of water management would take us far from 

 the field of aquatic entomology. For purposes of this 

 Introduction it will suffice to discuss the role of 

 insects and the status of insect problems in relation 

 to water management in the state. 



Mosquito and Gnat Control 



Mosquito control touches nearly all aspects of aquatic 

 biology and is a primary consideration to the aquatic 

 entomologist. The subject is so large and has been 

 fully dealt with in so many books that it will be 

 treated only briefly here. For fuller information the 

 reader is referred to the following: Herms and Gray 

 (1944), Bates (1949), Horsfall (1955), and CarpenteV 

 and La Casse (1955). A summary, Mosquito Abatement 

 in California, was issued by the Bureau of Vector 

 Control, State Department of Public Health (Bull. No. 

 VC-1, 1951). 



In the half century or more since mosquitoes were 

 found to be vectors of human diseases, control meas- 

 ures have been improved steadily and, at times, 

 spectacularly. To the earliest kerosene spraying 

 (L. 0. Howard, 1892) and Paris green dusting (Barber 

 & Hayne, 1921) were added methods for eliminating 



