THE VICTORIAN NATURALIST. 99 



NOTES ON AN ENTOMOGENOUS FUNGUS. 



These notes refer to the life-history of a small parasitic fungus of 

 possibly considerable economic value, since it attacks the larvae 

 of Agrotis infusa, A. breviuscula, A. munda, and several allied 

 species, all of them mischievous at all times, and in years of 

 abnormal increase causing the almost complete destruction of 

 cereal crops and grasses, English barley and various fodder grasses 

 being most liable to attack. 



They will strip a grass paddock, eating all before them, but in a 

 barley field their attention is directed more especially to a small 

 part of the stalk just below the ear, so that one or two grubs can 

 quickly cut off all the grain-bearing portions of the plant, leaving 

 the almost worthless leaves and stalk untouched. 



The fungus makes its appearance amongst these larva? from June 

 to January, but seems to be more common in June and July than 

 later on in the summer months. It appears to be closely related 

 to the fungus Emjmsa muscce found on the house-fly. 



When a grub is attacked, it usually climbs to near the top of a 

 tall head of grass, and remains there after death, firmly held on by 

 its feet. For some hours the larva is exteriorly unaltered, though on 

 closer inspection a minute white tuft or two may be occasionally 

 seen on the under surface of the thorax. After exposure for a day 

 two in the open air nothing but the dried shrunken skin will be 

 found, empty and brittle, still firmly adherent to the grass stem, 

 and looking like a piece of very narrow black ribbon about an 

 inch long. 



In order to observe the intermediate stages the insect when just 

 dead should be kept in a moist atmosphere, supported over a 

 piece of glass to secure the spores. Under these conditions about 

 fifteen hours will suffice for a complete change in the insect's 

 appearance. Its rotund body will have shrunken considerably, 

 and will be covered with a dense mass of fawn-coloured material 

 consisting of short cells from 9 to 15 /x. in diameter, containing 

 rounded globules. The glass for a distance of about a quarter of 

 an inch on each side of the insect will be found thickly covered with 

 spores, smooth, hyaline, pear-shaped to oval, averaging 25 x 15 p. 

 They preserve their shape and size even when dry mounted for 

 many months. 



As an instance of the economic value of this parasite, I may 

 mention that in a paddock near Windsor, in the year 1893, the 

 moths previously mentioned were unusually numerous, and the 

 number of larva? during the next season was also far in excess of 

 anything previously noted, but were so thoroughly kept in check 

 by the fungus that scarcely any moths could be found next year. 



I have records of the occurrence of this fungus on these larvse 

 at Ararat, Ballarat, Beech Forest, Melbourne, Millbrook, and 

 Woodend.— W. H. F. Hill, Windsor. 



