Presidential Address. T. Petch. 37 
and about ten species have been described*, parasitic on 
Lecanium, Pulvinaria, Aspidiotus, Chermes, Physokermes, Aleu- 
rodes, Icerya and Dactylopius. The majority of these belong to 
the Saccharomycetes. This group is one which invites the atten- 
tion of British mycologists, as all the existing records have 
been made in temperate countries—France, Italy, Bohemia, 
and Germany. 
The list of fungi which are parasitic on scale insects is already 
a long one, but there is every probability that it will be still 
further extended. The majority of the species are essentially 
tropical, and when more is known about the biology of tropical 
fungi, new forms may be expected to be added. From the 
specimens available in herbaria, these fungi would be considered 
rare, but it is generally possible, at least in Ceylon, to collect 
them in large numbers by searching specially for them. I have 
seen a tree of the Ceylon Patna Oak (Schletchera trijuga), on 
which nearly every leaf bore Aschersonia placenta, in some cases 
so crowded that the stromata had fused into a continuous sheet. 
The discovery of a single Aschersonia usually leads to the 
collection of dozens, or sometimes hundreds, if the bush is 
systematically examined, though of course disappointments do 
occur. 
No one who has collected these fungi in the tropics can fail 
to be impressed by the enormous destruction of scale insects 
which they bring about. A Septobasidium will wipe out all the 
insects on a badly-infested orange tree or tea bush. Cephalo- 
sporium Lecani will attack Lecanium viride on coffee over the 
whole of an estate. I have spent a morning in a Ceylon jungle 
which consisted almost entirely of Ebony trees, collecting 
Aschersonia placenta on the Ebony leaves, and have not been 
able to find a single specimen of the Aleyrodid on which it grew: 
the insect had been obliterated over an area of several acres. 
Again, in the jungle above Hakgala, Aschersonia oxystoma is 
common on the shrub, Sarcococca pruniformis, but although I 
have collected it there periodically for several years, I have not 
been able to determine what scale it is parasitic on. When a 
scale insect on a particular tree is attacked by a fungus, its 
destruction is so complete that one wonders how the species 
manages to survive. 
Under such circumstances, it is not surprising that attempts 
have been made to control the scale insect pests of economic 
plants by means of entomogenous fungi. The best known of 
these, in fact the only attempts which have been conducted 
on an experimental basis, have been carried out in Florida, 
where, since about 1896, the use of Aschersonia Aleyrodis and 
* See Buchner, Arch. Protistenk. xxvi (1912), pp. I-I16. 
