I20 THE APPLE LEAF HOPPER 



Should this hectle reach Minnesota, which is hkely, its occurrence 

 will be of such serious import at to call for a special publication, and 

 nothing need be said here upon remedial measures beyond the state- 

 ment that spraying with arsenicals (preferably arsenate of lead) just 

 as the grubs appear would be beneficial. 



SHADE TREES INJURED BY GAS. 



Wc figure here (the cut is from a photograph by J. S. Houser 

 and loaned us by the Ohio Experiment Station) a tree dying appar- 

 ently as a result of a leak in the gas main. This is quite a com- 

 mon sight in the streets of the Twin Cities, and this injury must be 

 carefully distinguished from that caused by insects. If one cannot 

 detect the presence of insects or their work upon the leafless branch- 

 es, and there is no evidenc^e of borers in the trunk, suspicion is at once 

 directed toward gas poisoning if gas mains are on that street, and 

 one must, in such a case, attack the gas company instead of making 

 preparations to wage war upon insects. A portion of the Ijark on the 

 trunk may peel ofif from trees so afl^ectcd. 



GENERAL SUGGESTIONS. 



All of our shade tree pests have not been discussed in this report, 

 attention having been paid to those for the most part notably in- 

 jurious in the last few years. 



Our Basswood trees are injured by a measuring worm known as 

 Hybernia tiliaria, Han. Oak trees this year (1908J have been in one 

 instance defoliated by a leaf-eating caterpillar, Symmcrista albifroiis. 

 Abb. and Sul, and are frequently attacked by the orange-striped Oak 

 Worms, and worms feeding on the Black Walnut (sent in pupal stage, 

 but i)robably Dataiia integcrriina, Gr. and Rob.) were received in the 

 summer of 1908. 



It is very evident that all leaf-eating insects may be killed with 

 arsenical sprays, or by hand-picking, or by cutting off the infested twig 

 and destroying the insects thereon, or by burning their colonies or webs 

 by means of a torch on a pole, or by crushing them with the gloved 

 hand. 



Eggs of many species can be collected in late fall or winter. 



Of sucking insects, lice can be killed by a spray of Ivory soap 

 dissolved in hot water (a five-cent cake in six or seven gallons of 

 water), or by kerosene emulsion (this must be prepared and used 

 with care), ^'oung scale insects can be destroyed by kerosene emul- 



