FORTY-FIFTH ANNUAL REPORT. 129 



INSECT PESTS. 



PROF. R. H. PETTIT^ EAST LANSING. 



I did not come here with a set speech but rather with the hope that 

 you might let me discuss your insect troubles with you informally. 



First of all, though, I want to say a word in reference to coarse 

 sprays. We are gradually coming to use coarser and coarser sprays 

 because we find that they do the work better. The reason is that we 

 are now using arsenate of lead instead of Paris-green. When using 

 Paris-green we were forced to use a fine fog-like spray and to stop be- 

 fore the tree dripped, in order to make the coarse particles of Paris- 

 green stay on the tree. Now with the finely divided arsenate of lead, 

 we can get plenty to stay or even if the tree drips and we can also 

 use a coarser nozzle and high pressure and thus make the liquid stick 

 better. You will also remember that I have been advocating home- 

 made lime and sulphur right along in fact have been something of a 

 crank about it. The home-made lime-sulphur carries a good deal of 

 sludge which gives body to the spray and keeps more of it in contact 

 with the insects. 



While there has not been very much new to report this year, I want 

 to say that we have found out one new fact of general interest. It 

 happens to be about the bean-maggot. This pest has been very trouble- 

 some all over the State during the past season. It works in the roots 

 and stems just after the beans sprout, sometimes killing an entire crop 

 before the beans even get a chance to make a start. It had been be- 

 lieved up to this time that the adult flies laid their eggs on the stems 

 as they pushed up above ground and that the maggots worked down- 

 ward from there. The infestation just past gave us the opportunity, 

 however, to establish beyond doubt the fact that the maggots are some- 

 times in the soil ready to attack the beans as soon as sprouted, since 

 some fields Avere destroyed before the beans even appeared above ground. 

 When this fact became apparent Mr. Whelan, field agent of the College 

 department of Entomology, made a careful study of the conditions un- 

 der which infested fields were grown. As a result of which we now 

 know that the most favorable conditions for the maggot are those fol- 

 lowing a late plowing of a clover-sod which has recently been heavily 

 dressed wtih fresh manure. Early idowed fields escape with little in- 

 jury. Fall plowed fields usually with none. Clover-sod with the old 

 stems and fresh manure seems to serve as a breeding place for the 

 maggots and if the field be fitted late then the beans sprout before the 

 maggots have time to become flies and disappear. 



Now, gentlemen, as I said before, I have not come here with a speech 

 to deliver. I want to be just as helpful to you as I can by discussing 

 with you the problems that you meet in your every-day experience. 



A Member: I would like to have a little information on the pear 

 psylla. 



17 



