


















' The fourth division, the rearing and study of native parasites 
poenemics, was really divided into two branches. The rearing of 
ive parasites was conducted by the Bureau of Entomology while other 
Boies, such as birds and mammals, were studied in cooperation with 
» UL S. Biological Survey, a man being detailed from that office to 
Brsee the work. 
‘The fifth division of work, that of parasite introduction, is one 
) , Gave us considerable hope for & control of the pest, but like: 
es is quite uncertain. As there is no other species of Hemileuca 
| occurs in numbers sufficient for parasite development we had to 
9k for parasites and predaceous enemies of altogether different 
jilies. several shipments of predaceous beetles ond tachinids were 
Ceived from the Gipsy Moth Laboratory, through the kindness of Mr. 
rgess, and while we do not know whether these will survive the north- 
nm New Mexico winters it is gratifying to note that several especies 
Calosoma took hold nicely, while the tachinid, Compsileura concinnata 
BS been successfully carried througa on Hemileuca larvae. 
The work, having been largely preliminary this past year, will be 
Mtinued during the season of 1914, and we hope with more desirable 
@ther conditions and a knowledge gained by the past summer’s exper- 
mce, to be able to accomplish much more during the coming summer. 
] V. L. WILDERMUTH. 
» iI was interested in Mr. Urbahn's formula for diluting dicewen, but 
think he has complicated the matter unduly. Since the two 100’s he 
Wes cancel, what is their use? Why not make the formula more simple, 
Present strength x Quantity to be changed = 
Desired strength 1 
Or better and more simple still use the following formula: 
ijired strength : Present strength 1; Quantity to be changed : X 
70 ; 95 He 20 Psa? 
But in any case this is a formula that is hard to remember, and 
Simplest formula for diluting alcohol which is given in most text 
joke is as follows: "To obtain a given per cent of alcohol through 
mution of a higher per cent with distilled water, subtract the per- 
mt required from the per cent of the alcohol to be diluted; the dif- 
rence is the proportion of water that must De added. Thus, if 35 is 
is per cent required, and 95 the per cent to be diluted, then 95 - 35 
60; hence 60 parts of water and 55 parts of 95 per cent alcohol are 
® proportion for mixing." (Guyer.) This is a very simple formula 
M@ one which can be remembered quite easily. I would suggest also for 
ie News Letter the value of the alcoholometer. This is a simple ap-— 
iratus costing about $1.50 with which the per cent of any alcohol can 
| obtained. We have had such an instrument and the two cans of alco- 
i| received from the supply department at Washington have tested 95 
8 and 94 per cent, respectively. Alcohol purchased at drug stores 
i liable to vary considerably and for this and other reasons an alco- 
jiometer is a handy instrument to have on hand, J. Jd. DAVIS. 
_ If those who applied for the plates mentioned on p. 3, December 
W s-Letter, have found that Plates 3 and 4 of the Vespidae are missing. 
ASSs will be Supplied them on application to the Chief. of Bureau. 
