212 OHIO EXPERIMENT STATION: BULLETIN 332 



From 4 to 6 pounds of paste or half the amount of the powdered 

 arsenate of lead should be used to each 50 gallons of water, and the 

 application should be made just as early as possible after the cater- 

 pillars begin feeding. For the first brood this will be about the 

 latter part of May and for the second brood some time in July. 



If considerable numbers of egg masses are observed during the 

 winter and the eggs appear healthy and virile, preparations should 

 be made to spray for the first brood. By making the poison appli- 

 cation at the time the first brood of young caterpillars are hatching, 

 not only does one make the attack at the most strategic time, but, 

 by thus eliminating the first brood of larvae, he may be reasonably 

 safe in assuming that the second brood will be light not enough 

 to require attention. Moreover, such a procedure conserves the 

 foliage of the tree so that the actual damage inflicted may be neg- 

 ligible, although the infestation may have been a severe one. 



Collecting the egg masses is sometimes practiced indeed, is 

 recommended by some entomologists as the chief method of control. 

 In theory it is admirable, but in general practice is a failure. If 

 the infested trees are small and the work thus may be done with 

 facility, the process is at once effective and practicable. The degree 

 of infestation also should be taken into consideration. If the tree 

 is moderate in size and but slightly infested, hand picking of the 

 egg clusters may be practicable ; but if the tree is heavily infested, 

 the picking process becomes expensive to a prohibitive degree. No 

 definite rule can be formulated as to just when hand picking is or 

 is not practicable; but under any but extraordinary conditions, if 

 a tree is at least 30 feet high, of spreading growth and moderately 

 to severely infested, spraying is more practicable than egg col- 

 lecting. 



The practice of some cities to pay school children or other 

 organizations by the measure for the collected egg masses has little 

 merit. Usually the material so collected is taken from porches, 

 fences, low down on tree trunks and similar situations from which 

 it is questionable whether the hatching caterpillars would be able 

 to make their way to the foliage of the trees. On one occasion the 

 writer had the opportunity to observe as a spectator a competition 

 among the different units of a boys' organization in an Ohio city 

 in a tussock egg-collecting campaign. Where one egg mass was 

 collected from tree trunks, fences, porches, etc. (comparatively 

 harmless situations), at least ten were left to remain in the treetops, 

 where conditions were ideal for their safe development. Such a 

 campaign furnishes excellent material for newspaper stories where 



