40 THE CANADIAN ENTOMOLOGIST. 



Host Plants. 



The plant most commonl>- ;ittacked in Nova Scotia is the Cow- 

 Parsnip {Ileracletim lanatum). The cultivated Parsnip {Pastinaca 

 saliva) is usually affected whenever it is grown for seed and the 

 Wild Carrot (Daucus carota) is also known to be attacked in America. 

 Besides the foregoing, Ileradeum spondyJium and Ileraclenm 

 sibericum serve as food plants for the insect in Europe. 



Natural Enemies. 



Riley states that no parasites were bred in the United States 

 by him, but mentions the following which haxe been recorded by 

 European writers: Cryptus flagitator Gv\.\ Pimpla heracUi and 

 Hoplismenus dimidiatus: Cryptus profligator C.r\-. and Ophion 

 vidnerator Gv\. Bethune was also unable to secure any parasites, 

 but states that the Hair>' Woodpecker (Piciis villosus) destroyed 

 many larvae and pupcC. Harrison states that the greatest natural 

 enemy is the earwig, which destroys the pupa*. 



At Truro we have reared a number of hymenopterous parasites 

 from this insect, but these have not yet been determined. 



Remedies. 



Bethune suggests dusting with hellebore for controlling the 

 Parsnip Webworm. Riley recommends spraying with arsenate or 

 the destruction of affected stalks. A. J. Cook says that a dilute 

 watering mixture of an arsenate is by far the best remedy; he also 

 recommends dusting with London Purple. Harrison believes in 

 destroying the w'ild plants and handpicking the parsnip flowers. 



Unfortunately we have not yet succeeded in finding any remedy 

 that will completely control this pest, though experiments on a 

 rather small scale were undertaken this season. The habit of the 

 insect in tying up the seed head with silk and working inside a 

 silken tunnel makes the work very difficult. 



Spraying with lead arsenate or Paris Green just as the larvae 

 were hatching had little apparent effect. Dusting with Paris Green 

 1 part to 25 parts or with air-slaked lime gave somewhat better results, 

 and when the umbels are open, it will prevent them from damaging 

 any new seed. It will not, however, effect the caterpillars in the 

 umbels which have already been tied up with silk. Cutting off 

 and burning affected seed heads, as has been suggested, would 



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