BUREAU or ENTOMOLOGY. 309 



feed upon cotton to some extent. Whether or not the bolls would 

 be attacked has not yet been ascertained, because the cool climate 

 prevailing there prevents the production of bolls on the plants 

 grown for experimental purposes. The fact that the insect has been 

 shown to feed upon cotton seems to indicate increased damage in case 

 it should eA'entually become distributed throughout the cotton-belt 

 States. This probability is given added weight b}^ the discovery 

 that under optimum temperature conditions the insect may undergo 

 its complete lif6 cycle in 30 days, and thus produce several genera- 

 tions each year. In fact, Del Guercio of Florence, Italy, told the 

 writer in June that there are three generations a year there. 



Generally speaking, at the close of July of this year the infestation 

 in New England appears to be not quite so heavj^ as during 1919, 

 although some few tields are still heavily infested. 



That the insect may be easil}^ transported into new territory by 

 flood waters seems to have been amply proved by the fact that pupae 

 which were submerged in water for three days produced adult moths. 



At the time of writing a total of 197 men are employed in the 

 control work. 



During the year several efficient pieces of machinery have been 

 evolved for the purpose of destroying in the field infested materials 

 such as cornstalks and stubble as well as weeds. One of these is a 

 crushing apparatus through which the infested material is run and 

 which applies a pressure of 90 tons to the square inch and is capable 

 of handling 12 to 15 tons a day. Two of these machines arc at pres- 

 ent in operation. Another efficient piece of machinery is an oil- 

 spraying burning machine of high power, capable of burning a strip 

 12 feet wide at one application, and with which it is possible to treat 

 12 to 15 acres in one day per machine. 



1 ntroductioii of fore'icin 'parasites of the corn horer. — During the 

 early summer of 1919 a preliminary investigation was made of 

 European conditions, and a trained" observer was established at Auch, 

 in the south of France, to study the native parasites and to send 

 them to this country in the effort to establish them in the infested 

 parts of JNIassachusetts. Ihree species of parasites were found, 

 and one shipment arrived in the autumn and the parasites were 

 liberated in eastern Massachusetts. In May. 1920, the writer went to 

 Europe and visited the regions in which the corn borer occurs in 

 Belgium, France, and Italy, and arranged for the stud}' of the native 

 parasites at several points. He found that in Italy especially, where 

 corn is extensively grown, the corn borer was always present in the 

 fields, but in small numbers, and that nowhere was it necessary to 

 take measures for its suppression. This indicated the existence of 

 natural control, and it was found that four species of native para- 

 sites are known to the Italian entomologists. Arrangements were 

 made for the shipment of parasite material to the bureau's agent at 

 Auch, for comparison with the forms occurring at that point, and 

 if it is found desirable other small parasite laboratories will be 

 started in the south of Europe. 



Ctrasshoppeks. — Gretit numbers of grasshoppers, belonging princi- 

 jially to the species Melanojthis aflanis and Camnnla pelhirida^ have 

 coiitinucd to assail the crops in North Dakota. The northern and 

 western counties have been most heavily affected, although consid- 



