INSECT NOTES FROM MINNESOTA FOR ItMJB. 15 



SO treated made an excellent showing*. A man can treat G to 8 plants 

 per minute. This treatment, of course, would not be practicable on a 

 large acreage. 



The small red rnite TromhUlhim .^irahriim Say was observed to be 

 extremely active in sucking the eggs of the Phorbia. On May 15 an 

 assistant in the field reported this mite as very numerous, averaging 

 about two to a plant, and occasionally four or five were observed 

 about one plant. On this date a large number of eggs examined had 

 evidently been sucked. Frequently there would not be a single good 

 (^gcr found aroimd a ])lant. out of a lot of a dozen or more that had 

 originally been laid there. 



We have obtained from (ho l)urrow of a maggot a cynipid para- 

 site, Pseudeuc(£la gillettcl xVshm. ; we have also bred from a pupa- 

 rium Fleet isevs sp. — identified by the American Entomological 

 Society, of Philadelphia. We have also included among the pre- 

 daceous enemies of Phorbia the carabid beetles Pterostichus coracimis 

 Xewm., P. hicuMan(h/,s Say, Agonoden/.s i><iUipex P^ab.. and Amara 

 bnpimMicollis Say. since immediately after being brought in from 

 the field these beetles fed ravenously upon the maggot. These species 

 were })resent in large numbers in almost all of our cabbage fields, 

 as were also Heterothops fiiinigatus Lee, Ldthrohhim, anale Lee, 

 and Bemhi<1ii(m (juadrimacidatum L., although these three latter 

 beetles Avere not actually observed to eat the maggot. Plants in sandy 

 soil appeared to suffer more, everything else being equal, than those 

 planted in heavy soil. 



RECENT OBSERVATIONS ON THE USE OF HYDROCYANIC ACID GAS. 



One sometimes has occasion in fumigating mills of small size to 

 drop packages of cyanide into jars containing acid, and at such 

 times the question as to how much time elapses between the drop- 

 ping of fhe cyanide, inclosed in a double sack, and the giving oif of 

 (he deadly gas is an important one. In doing the work personally 

 I have allowed fifteen seconds as a conservative estimate in this direc- 

 tion and acted accordingly. To place this matter l)eyond any doubt, 

 however, we have this fall made several trials, timing the interval 

 between the dropping of the double bag of cyanide into the jar and 

 the first appearance of the fumes, with surprising results. A double 

 manila sack was used in each case — that is, one sack inside another — 

 and various makes of sacks. In each case the liquid was fairly 

 warm, but no observation was made on its exact temperature. We 

 found in a series of trials that this interval varies from twenty-nine 

 seconds, the lowest period, to four minutes, the latter being the 

 highest interval, the variation evidently being largely due to varia- 

 tions in the thickness and character of the paper of which the sacks 



