S U M M A R YT h e life-history of L. auripila, as a pest of mushrooms, is outlined and an explanation is given of the different types of damage caused. T h e most satisfactory control is based on the incorporation of insecticides in compost at spawning. Emulsions of chlorfenvinphos and diazinon at 50 ppm are lethal to young larvae for at least 7 weeks but granular formulations of the former must be applied at roo ppm to achieve comparable results. Drenches of 0.01 yo malathion, applied at about 40 gal/Iooo ft2, are effective against larvae in the casing.

S U M M A R YFour species of Coccinellidae, Adalia bipunctata (L.), Coccinella septempunctata L., Coelomegilla maculata de G. and Cycloneda sanguinea L.,

SUMMARYPopulations of phorid flies on an experimental mushroom unit were sampled simultaneously in both spawn‐running and mushroom cropping‐houses by sticky traps. Comparison between these populations showed that each reached a maximum about August and that the rate of increase, as measured by the ratio between them, varied from 22 × (at the beginning of February and in mid‐August to 115 × (at the beginning of June and the end of December). Population growth within a crop was assessed from the peaks plotted from weekly catches. Three such peaks could be seen, starting from initial numbers which were high, on average, at casing but with little increase after the seventh week of cropping. However, population growth within crops, found by pooling data for different seasons, showed logistic increases though slopes varied from low, for May to June‐spawned crops, to high for October spawning. Wide variations occurred in the proportion of the total flies represented in the initial catches in the first wk after casing.Partial regressions were examined for the numbers caught in cropping‐houses on those taken in spawn‐running rooms throughout the year. Catches for crops spawned during June to September gave lower slopes for high cropping‐house populations. Spawn‐running room catches showed a linear relation with outdoor 9.00 a.m. B.S.T. temperature and cropping‐house numbers a logistic relation, a better fit obtaining with temperatures at spawning rather than 5 wk later during cropping. Catches during spawn‐running were correlated with those during subsequent cropping and these with catches made during the previous crop on the unit, irrespective of site. Since it was bimodal, rate of increase between spawn‐running and cropping‐houses did not correlate with outdoor temperature but revealed some very high catches in winter. Many flies were trapped in the cropping‐houses early in the year when flies were absent from spawn‐running rooms. Evidence for movements within farms is discussed, especially with respect to overwintering of the phorid, which validates routine trapping of both populations.

SUMMARYInsecticides incorporated into mushroom compost, using a spawning machine, are seldom mixed uniformly enough to achieve satisfactory pest control. The mixing efficiencies of various application methods and machines were investigated by mapping the distributions of fluorescent granules and emulsions under ultraviolet light. The pattern in which granules were applied to a compost block greatly affected the distribution after mixing but even uniformly peppering the surface resulted in acceptable concentrations in only 49% of the compost. Mixing twice increased this to 57%. With three times as many smaller granules, 89% of the compost was acceptably treated. Watering or spraying the compost with emulsions gave poor distributions except when the spray was directed into the spinner, which acceptably treated 83%. A machine which threw compost upwards into a hood beyond the spinner before it fell into a tray, gave better mixtures than conventional machines.The granule distribution affected the control of Heteropeza pygmaea larvae. Virtually complete control was obtained by peppering diazinon granules on to compost at 50 ppm a.i. and then mixing twice through a spawning machine.

THE phorid Megaselia hdterata Wood has been a widespread pest of mushrooms since 1953, when it caused severe damage to commercial crops m southern England. Since that time it has been commonly known as the " Worthing Phorid " or " Mushroom Fly ". Unlike M. nigra Meigen, which attacks the sporophore and was the species referred to in the older literature dealing with pests of mushrooms cultivated outdoors. M. hdterata infests the mycelium. Although present in small numbers throughout the year on mushroom farms, it is only common and potentially destructive between June and October. To permit uninterrupted investigations on the biology and control of this pest a continuous rearing technique is necessary. Moreton and John (1955) reported rearing this species in 3in. X lin. tubes containing a small quantity of spawned compost. We had diflficulty in obtaining eggs under these conditions, and investigated the factors limiting success.Discovery of the parasitic eelworm Bradynema sp. within the body cavity of many adult flies (Hussey and Wyatt, 1958) revealed that the reproductive potential of infested females was often reduced from about 50 to only two or three eggs. The eelworm enters its host during the first or second larval instar by boring through the body wall. The eggs of M. hdterata in the compost are unaffected by the free-living stages of the eelworm, so eggs were collected by exposing spawned compost on heavily infested farms for a few days and then extracted by agitating the compost in water above a sieve within a Baermann funnel. M. halterata males infested with Bradynema are often impotent, and as virgin females may lay about 30 infertile eggs these are commonly extracted from compost. Successful cultures depend, therefore, on the recognition of fertile eggs which are translucent, whereas infertile ones are cloudy and almost opaque.The proportion of M. halterata infested by Bradynema varies from place to place and season to season, but 80 per cent infestation has commonly been found. Colonies initiated with wild flies in small culture vessels are almost invariably infested. Within the small volumes of compost used, infestation of later generations is rapid and increasingly complete, so that such colonies inevitably die out after a few generations. It is possible that Moreton and John collected their material from a population of M. hdterata unaffected by this eelworm and therefore avoided the difficulties now often encountered. Indeed, evidence from recent outbreaks suggests that the absence of the eelworm in 1953 may well have accounted for the severity of the early attacks.The degree of mycelial colonization of compost has also been shown to influence its attractiveness to female M. halterata for oviposition (Hussey, 1961). Mycelium must be actively growing to achieve optimal results and when the compost has been permeated with mycelium the females will not oviposit. This may be a reaction to the lack of developing hyphae on which the young larvae feed, or it may be a response to the lower moisture conte...