406 Phylum Arthropoda 



leaving the larvae. Where quantitative collection is unnecessary, many 

 larvae may be located by turning the mud with a fork or trowel. In 

 the latitude of northwest Arkansas larvae are most easily found and col- 

 lected in numbers during March and April. 



Pupae occupy the same habitat as the larvae from which they develop 

 and may be collected by the same means. Larvae of those species which 

 live in mud near water usually move 6 inches or a foot farther back from 

 the edge of the water before pupating. Pupae usually are difficult to 

 find, probably because the stage is short, and it seldom happens that many 

 individuals of a given species are in the pupal stage at the same time. 

 There are a few exceptions to this among the species of Chrysops. 



Eggs of the Tabanidae also occur in very diverse situations. Vegeta- 

 tion, especially grasses, sedges, and flags, growing in the water or on the 

 banks within 6 feet of the water are favorite oviposition sites for several 

 species. Sticks or other debris similarly located are also frequently used. 

 Hundreds of egg masses of Chrysops flavidus and Tabanus lineola have 

 been seen on rice plants in flooded fields. T. vivax places its egg masses 

 on rocks or debris protruding above the surface of very rapidly flowing 

 water. The same site is frequently chosen by several females of this 

 species so that great compound egg masses containing over 100,000 eggs 

 are sometimes found. T. sulci jrons often places its eggs on the under 

 sides of small tree limbs growing 6 to 10 feet from the ground, and not 

 necessarily near water. Goniops chrysocoma places its eggs on the under 

 sides of leaves of trees, frequently using maple. The eggs may be on a 

 seedling only 2 feet high, or 30 feet up in a large tree. Large numbers 

 of egg masses of various species have often been found on the under 

 surface of concrete bridge arches. Ovipositing females of both Tabanus 

 and Chrysops have been taken under bridges. 



REARING METHODS 



Engorged female flies collected from animals will usually oviposit 

 within a week after capture if kept in a suitable cage. A cage which has 

 proven successful for several species consists of a 1 -gallon stone jar, 

 into the top of which is closely fitted a cylinder of screen wire about 

 18 inches long and the diameter of the inside of the stone jar. This 

 cylinder is provided with a muslin cover held in place by a rubber band. 

 The stone jar is filled % full of soil and a medium-sized plant of some 

 tall grass set into it. A large or bushy plant makes it difficult to find 

 the egg masses. A small wad of cotton soaked in very dilute honey is fas- 

 tened in the cage. Some species will oviposit more readily if the cage 

 is flooded so that water stands above the soil. The cage should be kept 

 in the sun for most species. It is possible that smaller cages may be 

 used, since oviposition was once secured accidentally in a glass vial in 



