INSECTS AFFECTING PARK AND WOODLAND TREES 



41 



with which the cubic contents may be calculated. Several box tents covered 

 with canvas or even roofinor paper have been devised. These are provided 

 with frames and either constructed with a tlexible hood so that they can he 

 dropped entire over trees or else with a removable sidi; which can be quickly 

 and tightly clamped to the frame. 



Directions for spray iiii^. In order to spray trees successfully, certain 

 rules must be observed. Apply the poison at the time the insects begin to 

 feed and where they must eat it if the tree is attacked. Early spraying not 

 only prevents much injury to foliage but it is likely to be fully as effective 

 because young caterpillars as a rule succumb more easily to poisons. In the 

 case of certain insects, it is best to throw the spray on the under surface of 

 the leaves so far as possible, as some young caterpillars and elm leaf beetle 

 grubs in particular, prefer the tender lower epidermis. Do thorough work, 

 that is, try to cover every leaf with the mixture and spray till the tree begins 

 to drip, but no more. The finer the spray, the better, as a more even distri- 

 bution is insured. The poisonous mixture must be kept agitated while 

 spraying is in progress. Good work can be accomplished with hand 

 pumps, though a power spraying apparatus is the best and plenty of hose is 

 essential, as a fine spray can not be thrown far and it is therefore usually 

 necessary to do more or less climbing. Remember that very much depends 

 on the man at the nozzle and insist on having one who can be relied on. 

 It is the poorest economy possible to put a cheap man in this responsible 

 and somewhat disagreeable position. It is comparatively easy to give 

 directions but the man who faithfully and intelligently carries them out is 

 not often found, and he who will temper his work with judgment is a rarity. 



Cost of spraying trees. Several years ago we took some pains to ascer- 

 tain the precise cost of spraying in the hope of encouraging those to 

 whom the expense seems a serious item, and it is pleasant to record that 

 it is much lower than had at first been supposed. Dr Smith, of the New 

 Jersey agricultural experiment station, kindly supplied the following data in 

 1898. The elms on the college campus at New Brunswick are 50 to 75 

 feet high and were sprayed at odd times by the janitors, about an hour 



