98 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
Common laundry soap.50 pounds 
Water. 3 gallons 
Flake naphthaline.25 pounds 
Flour. 2 pounds 
Place the soap in the water over steam-pipes and allow it to soften for a few days. 
Use a potash soap which will form a smooth mixture, not a soda soap since the latter 
becomes jelly-like. Then place in a double boiler (we use a medium sized wash- 
boiler placed inside a very large one) and cook until the temperature reaches 180° 
Fah. Stir in the flour and add the naphthaline and bring the temperature to 180° 
Fah. at which temperature the naphthaline will have melted, the melting point of 
naphthaline being 176°, then cool as quickly as may be, stirring the mixture occasion¬ 
ally. 
The more rapidly the mixture is cooled the smaller will be the crystals of naphtha¬ 
line. 
In our experimental work this mixture was made up during the winter and stored 
in air-tight drums. It should be applied with a brush after warming and thinning 
slightly to the consistency of heavy cream. In our trials, applications were made 
every three weeks beginning on June 1st, and in no case thus far has any injury to the 
trees resulted. At the same time almost no flat-heads have been found in trees so 
protected although they abounded in the checks and in some cases had done very 
serious injury to young trees in the same orchards previous to the application. Our 
tests have covered a period of about four years and have been made on several 
thousand trees. 
It seems likely that it will be possible to extend the interval between treatments 
without losing a reasonable insurance against attack and perhaps the same treat¬ 
ment will protect other borers of the trunks and limbs of various trees. 
R. H. Pettit 
Michigan A gricultural College 
A Parasite of the European Rose Slug Egg. The European rose slug, Caliroa 
aethiops Fabr., is very destructive to rose bushes in Lawrence, Kansas, every season. 
It renders most unsightly all bushes that have not been protected by sprays. In 
early May, 1919, my attention was called to the fact that a large number of the egg 
blisters were brown, or shiny black. Many egg-bearing leaves were gathered and 
brought to the laboratory for study. From these black shiny eggs there emerged 
the little wasp parasite that has been determined for me by Mr. Rohrer, as Tricho- 
gramma minuta Riley. This parasite has been reported from eggs of A letia argillacea, 
Odontota suturalis, Plusia brassicae , Heliothis armigera , Papilio glaucus , Vanessa 
atalanta, Basalarchia archippus and Pteronidea ribesi ; the last, of course, a sawfly. 
The eggs of the rose sawfly on one hedge of rose bushes, were quite commonly 
parasitized, counts showing about twenty-five per cent parasitism. Many other 
sections of the town were examined, but no parasitized eggs found. Each summer 
since 1919, we have looked carefully for parasitized eggs on the hedge where they had 
been found and elsewhere, but so far, have not taken any parasites. 
The parasitic wasps emerged from parasitized eggs brought in from the bushes, 
in from one to six days. From one to three wasps issued from each egg. On several 
occasions I witnessed the emergence by means of the binocular microscope. From 
one egg, three came forth, one following the other in quick succession. The tiny 
