1921.] PUBLIC DOCUMENT — No. 31. 37 a 



been found and promises to prove sound. If so, the data 

 already accumulated will be of great value. Added to this as 

 collateral items, observations on the dates of appearance of 

 many of our other common insects and of the development of 

 various plants in the spring promise much of interest along the 

 same line. 



Tests of Standard Insecticides. — Studies on the burning of 

 foliage by insecticides are drawing toward an end. The results 

 thus far are being tabulated and prepared for publication. 



Studies on Digger Wasps. — These studies are progressing, 

 though slowly. The project is a much larger one than was at 

 first supposed, and with little time available for it, any marked 

 advance in a single year is impossible. 



The Squash-vine Borer. — This pest has caused a large amount 

 of injury in Massachusetts the last few years, and a study of 

 the insect and methods for controlling it have therefore been 

 taken up this season. It is too early as yet to expect results, 

 but several facts which may prove of value have already been 

 obtained. 



The Squash Bug. — This pest has also been studied to some 

 extent the past summer. Work on it will be continued next 

 year. 



Studies of Spray Materials. 



Studies of several materials used in spraying were made 

 during the season, and the results follow: — 



Aphicide. — There have been times when nicotine sulfate 40 

 per cent was not available on the market, owing either to an 

 unusual demand or faulty distribution. At such times an ef- 

 fective substitute to use against aphids is desirable. Kerosene 

 emulsion, employed for many years for these insects, is trouble- 

 some to make, and frequently fails to give good results. Any- 

 thing which is an effective aphicide and also reasonable in 

 price is, therefore, desirable to add to our list of insecticides. 



Aphicide is a new material manufactured as a substitute for 

 the nicotine sprays in controlling plant lice, and it was there- 

 fore tested during the season. Two samples were provided, one 

 apparently more concentrated than the other. Both were clear 

 liquids, the (presumably) weaker being almost colorless, the 



