653 NEW JERSEY AGRICULTUEAL COLLEGE 



tho Inborn toi'v, niul iho result \vns the ilestruetion of nearly all 

 [\w lnrv;e in nil save one of the pools. Egg boats were also placed 

 on the surface of treated water in the laboratory experiments, and 

 these failed to hatch, while others from the same lot and placed on 

 uutrentcii '.vnter developed Inrvtv normally. 



Tiie not result of these experiments was that if used in suffi- 

 cient quantity the "Killnrvtr" does really kill mosquitoes in all 

 stages, nnd the strong odor of :!unuonin rising from tlu^ surfnce 

 will probnbly prevent ovi])ositi<ui for a short time. 



Two days Inter, July 20th, Mr. Grossbeck re-exnmined the lot 

 pools, i'ouud th(Mii partly di'ied iq>, but what water reuuuned no 

 longer hnd nn nlkaline reaction, and there was a new crop of 

 young wrigglers. In other words, the pools were not protected 

 for more than twcMity-four hours. 



This is not renlly sur[)rising, for, since the killing power of the 

 nuiterinl depends largely upon the aunnonia developed, it would 

 cease to be effective as soon as all the ammonia was dissipated, 

 and that goes xory rn]udly. 



As coiiip;ir('il with jtetroleuui, "ivilhirva^" is no more etfcH?tive, 

 and is, in I'nci, less certain, whore pools are irregular and encimi- 

 bori'd w iih \eg(>tation. Nor does it protect for so long a time, for 

 in a quiet pool the oil will serve for a week or two, while the 

 "Killarva'" disappears altogether in a ilay or two. Its only ad- 

 vantage over the oil is its cleanliness, and it may have a distinct 

 and useful tield in dealing with those woodland pools in which 

 only a single spring brood develops. In this case any material 

 that will with ceriniuly kill otT the larva^ before they have a chance 

 to cou\i' lo maturity will serve to free the treated forest district 

 for an entire season from the offensive species that infest it. In 

 such ]daces as the Essex countv parks its euq>loynieut would be 

 well repaid. 



