ENTOMOLOGY

BIOLOGY AND HABITS OF HORSE FLIES 241ing a cotton stopper into the mouth of the vial tight enough to hold theegg mass in position. When the larvre emerge they fall into the waterwhere they will remain alive for several days if undisturbed. The younglarvre of Tabanus phaenops and those of the unidentified species fromAlturas sink to the bottom of the water and remain there alive and ingood condition, without rising to the surface for air. On the other hand,newly emerged larvre of Tabanus pwnctifer (plate XX, fig. 2) remain atthe surface of the water constantly. In aU these three species, the firstmolt occurs within a very few hours after hatching, and the cast skinsare to be found floating in the water.Mitzmain is the only author I find mentioning the molting of Tabanuslarvre. He noted S molts in the case of the larvre of Tabanus st1iatus inthe Philippines. The first molt begins with larvIE 7 days old, the majoritymolting before the 10th day. The second molt usually occurs after aninterval of at least 4 days, and in some larvre as much as 8 days, that is,when 1'5 to 18 days, old. The third molt, which discloses the pupa, isvery variable as to the time of its occurrence, some individuals not pupatinguntil S months after the larvre emerge from the eggs, the majority,however, pupating in a much shorter time. In fact, Mitzmain reared fliesfrom deposition of egg to adult in 52 days.As was stated in the beginning, the eggs are deposited above situationssuitable for the development of the larvre, so that the young larvrewhen they dr~p from the egg mass immediately find themselves at home.If it is a species which lives in mud under water, the eggs will be foundoverhanging water, and' upon dropping from the eggs the young larvrewill simply sink through the water to the mud beneath. If it is a specie~which prefers mud not submerged, the eggs will be found in the rightposition and the larvl!! upon dropping to the mud, immediately burrowinto it. .'I'he food of Tabanid larvre consists of small crustaceans and otherminute forms of animal life of a soft texture. As the larvre increase insize they may take coarser food. In breeding jars, I have seldom usedany other food than earth worms cut into sections, and such small formsof life as may be gathered up with the mud placed in the jar. The larvreare cannibalistic and eat each other readily. l\Iitzmain states that thelarvre of Taba1llU8 striatus seem to prefer their own kind even when otherfood is available. For this reason it is well in attempting to rear larvreof this genus, to place but one larva in each rearing jar. I have"however,in some cases successfully reared more than one individual in the same jar.Sometimes it is much easier to locate the larva! of a given species thanthe eggs. In most cases in my own experience, I have found the larvrefirst. In the mountain valleys of Eastern California where considerableareas of pasture land are irrigated, the larvre of TabOlnus phaenops are to