April, ’23] 
PROGRESS REPORT OF INVESTIGATIONS 
223 
various chemicals and other substances. Records of the number of 
flies in each jar at different times each day, the presence of eggs and 
larvae and the ovicidal and larvicidal effects of the chemicals were 
made. In addition to testing the chemicals directly on meat in jars, 
experiments were made in which they were incorporated with carriers 
such as mineral oils, petrolatum and inert powders, and applied to the 
meat or to wounds. 
Some two hundred substances were tested and of these a few such as 
acetone and amyl butyrate apparently have attractive qualities for 
flies. Others, such as furfural, safrol and salicylic aldehyde, several 
essential oils, viz., anise, cassia, clove, citronella, fennel and sassafras, 
various pine oils, certain camphor oils and artificial mustard oil have 
shown definite repellent value. The pine tar oil having the greatest 
repellent actions has not been determined nor have we determined the 
exact status of all the various substances mentioned. 
Several chemicals have been found to possess a larvicidal effect. 
Among these are nitrobenzene, bromoform, furfural, safrol, pyridine, 
sassafras oil, salicylic aldehyde and others, but many are too toxic to be 
used on animals. It will be noted that repellent and larvicidal actions 
are, in some instances, shown by the same material. Some larvicides 
are not sufficiently toxic to larvae to warrant their use on wounds and 
many lack the volatility needed to produce a larvicidal action deep in the 
tissue. 
Of the larvicides for wound treatment 100% benzol has been found 
more satisfactory than chloroform, xylol or carbon tetrachloride. 
Cresols and phenols are not to be generally recommended. Bromo¬ 
form, while satisfactory for use on wounds, is very expensive. 
The first practical problem was to find satisfactory materials for 
application to animals infested by the screw worm fly. These materials 
must exert repellent properties for several days, i. e., until the wound 
heals and therefore is not attractive to flies. They should also be non¬ 
in jurious to the host and preferably have larvicidal action. They must 
adhere well and possess certain other properties. Of the various 
mixtures tested several have shown some value and one composed of one 
part of furfural and four parts of pine tar oil has proven very satisfactory. 
Another economic phase of the problem is to find repellents suitable for 
use in protecting meat and other food stuffs from fly contamination. 
The second practical problem was to find effective bait for blowflies. 
This bait must be suitable for shipment and for use in various places 
where flies may be trapped, such as around slaughterhouses, on ranches, 
