OBSERVATIONS ON THE LIFE HISTORY AND BIOLOGY OF <i>TIPULA LATERALIS</i> MEIG.

The occurrence of large numbers of larvae of Tipula lateralis Meig. in watercress beds has not hitherto been recorded. Observations on commercial beds and laboratory experimental work show this species to be primarily a saprophyte feeding on rotting submerged cress leaves, though it can develop during the final instar on green cress. Populations as high as 250,000/acre do not affect cress beds adversely.There are two generations a year and probably a partial third. The life cycle can be completed in 63 days. Mating and oviposition are described, the preferred site for egg laying being on wet soil. The average number of eggs is over 500. The egg and first‐instar larva are described for the first time. There are four instars, the anal segment of the first being radically different from that of the remainder. It has been shown that pupation cannot take place under water as previously stated.