TABLE 7 5 Monthly changes in the ostracod fauna of temporary po 

 (after Hoff 1943). 



nfral Illinois. The ponds 



Ostracod species 



March March April April May May June June July 

 9 17-20 1 15 4 18 9 22 10 



Cyphcercus reticuatus 

 Cypria turneri 

 Candona simpsoni 

 Candoiia fossulensis 

 Candotia distincta 



Candoiia indigena 

 Candoiia biatigulata 

 Cypria iiiaculala 

 Cypria opthalmica 

 Cypridopsis vidua 



Candona suburbana 

 Cypria obesa 



or bare ground near water ; on hatching, the larvae 

 proceed into the water. Here they stay for a full 

 year, after which they leave the water and pupate 

 for several months in a hollow that they scoop out 

 of moist earth. The adult does not live over winter. 

 Dragonflies may fasten their eggs to plants below or 

 above the water surface, puncture leaves or stems 

 for egg insertion, oviposit eggs in the bottom, or 

 may scatter them through the water and over the 

 bottom. The naiads hatch out in about three weeks 

 and are of varied forms and sizes. Dragonfly naiads 

 may be divided into three groups on the basis of their 

 habits ; the climbers that crawl through the vegeta- 

 tion ; the sprawlers that lie half buried in the mud 

 with legs extended and backs covered with silt : and 

 the burrowers. They all undergo several molts under 

 water, some forms living 1 1 months in this stage. 

 For their last molt they crawl up the stem of some 

 plant or onto a rock on the shore, molt, and emerge 

 as adults. They live for a few weeks only. Adult 

 dragonflies commonly feed on adult mosquitoes, and 

 the naiads feed to some extent on the mosquito larvae 

 (Needham and Westfall 1935). 



Aquatic beetles commonly attach their eggs to 

 water plants or bore holes into plant tissues to hold 

 them. Some hydrophilid beetles make floating silk 

 cocoons containing many eggs, anchoring these co- 

 coons to surface plants. Beetle larvae live only a few 

 weeks before they leave the water and pupate in 

 characteristic mud cells that they build for them- 

 selves. Pupation varies from a few weeks to several 

 months, depending on the temperature, before emer- 

 gence of the adult occurs. The adults are the chief 

 survivors of the winter but sometimes eggs or larvae 

 live through it, too (Miall 1934, Balduf 1935, Rice 

 1954). 



Mosquitoes reproduce abundantly in marshes, 

 ponds, or even in small pools, tree holes, or other 

 water-holding depressions. Some species of mos- 



quitoes lay hard-shelled chitinous-covered eggs on the 

 ground which are capable of withstanding freezing, 

 extreme heat, and drought but hatch very quickly 

 after being covered with warm water. In water, eggs 

 may be laid singly or in rafts. The adult female 

 Ciilex vexans stands at the margin of the pool or on 

 some floating object and deposits as many as 300 

 eggs. The individual eggs are cigar-shaped and are 

 placed vertically to form a floating raft. They fit to- 

 gether so snugly that the surface film of water does 

 not penetrate between the eggs, and the surface of 

 the raft is dry. The larvae hatch in 12 to 28 hours 

 and hang head down from the surface film. Vibrat- 

 ing vibrissae continually sweep food particles into 

 the larval mouth. The respiratory tube at the pos- 

 terior end of the body penetrates the surface film and 

 also prevents the body from sinking. At other times 

 the larvae may suspend themselves from the surface 

 film, dorsal side uppermost, and feed on floating ma- 

 terials (Renn 1941). After 3 or 4 molts (5 to 8 

 days), the larva changes into a quite differently- 

 shaped pupa, which hangs from the surface film by 

 two respiratory tubes proceeding from the thorax. 

 The winged adult may emerge in 2 days. Some spe- 

 cies may have seven broods per year. 



Sexual and other behavior of mosquitoes varies 

 considerably among species (Horsfall 1955). Ordi- 

 narily only the female mosquito bites, this to obtain 

 the blood nourishment necessary for egg-laying. The 

 male feeds only on plant juices. Studies made on 

 marked individuals of Aedes vexans showed that 73 

 per cent of the individuals confined their activities 

 to within a radius of 5 miles (8 km), but that 19 

 per cent traveled 5 to 10 miles (8-16 km) and some 

 even to 16 miles (26 km) away from the point of 

 marking (Clarke 1937). Other species, however, ap- 

 pear not to have such wide ranges. 



The pulmonate snail Physa gyrina lays its eggs 

 in the spring when water temperatures reach 10°- 



Ponds, marshes, swamps, and bogs 



