80 STATE BOARD OF AGRICULTURE. 



merely a pruning from which the tree recovers quickly. The insect ap- 

 pealed in only a few counties iu the southern part of the State. 



The wet spring has brought about another change in the insect popula- 

 tion and depredation, viz: Grasshopper and flea-beetles and all hissed* 

 which flourish in hot. dry weather, have not been in evidence but plant-lice 

 on rose, corn, potato, encumber, peas, maple and on many other plants 

 have had full swing. 



Mosquitoes have been worse? than in years before, and especially in 

 places where they usually are not to be seen at all. In many localities 

 where thev are almost unknown as a rule, thev swarm this year. An 

 experiment has been commenced at the College, the object of which is to 

 find out some facts about the habits of mosquitoes and to test the effi- 

 ciency of petroleum against the larval and pupal stages. An oil known as 

 light fuel oil, a product of petroleum, has been used on many ponds and 

 pools, spraying it on at the rate of one ounce to fifteen square feet of water. 

 The result has been perfectly satisfactory so far as its effect on the mos- 

 quitoes is concerned, as all of them are killed, but unfortunately, the 

 insects drift with the wind or fly to some distance, thus infesting the Col- 

 lege grounds in spite of the care observed. The College is surrounded with 

 many marshes and it is quite likely that some of these will have to be 

 drained before very effective work can be done. The results of this work 

 will be published more in full at a later date. 



Early in the spring it was found that much damage to young clover 

 had resulted from field mice, which ate off the stems at the crown. At 

 the request of Director Smith the subject was investigated and remedies 

 were proposed. It is hoped that during the coming fall some experi- 

 ments may be tried here on the grounds. 



Several insect diseases of considerable importance have been at work, 

 viz: A new species of Isaria on Lecanium longulum in the greenhouse, 

 a disease on the clover-leaf beetle larva, a disease on the seventeen-year 

 locust, and one on the plant-louse on potato. All these are of first class 

 importance and have considerable influence on the damage done by their 

 hosts. 



One week was spent in the winter in lecturing at farmers' institutes. 



Kespectfullv submitted, 



R. H. TETTIT, 



Entomologist. 

 Agricultural College, Mich., 

 June 30, 1902. 



