19 



NATUKAL ENEMIES. 



A single parasite of this species has been observed, the only natural 

 enemy that appears to be known for it. Among a lot of larvae from 

 Libonia, Pa. , a cocoon was found May 19, which gave the imago May 

 27. It was identified by Mr. Ashmead as a species of Synetaeris, an 

 ichneumonid genus related to Limneria. 



REMEDIES. 



Hand-picking. — The greenhouse leaf-tyer can be controlled in green- 

 houses by hand-picking or trimming away and destroying all infested 

 leaves or other portions of plants as often as they are detected. This 

 has been successfully practiced in a number of cases, one of which has 

 already been mentioned, but it is somewhat laborious. Mr. Wilson 

 wrote in regard to this species that he entirely rid his greenhouse of 

 it one season by hand-picking. 



Attracting moths to lights. — Another method of checking the increase 

 of the species is by attracting the moths to lights placed in the green- 

 houses at night. This method is in practice by at least one of our 

 correspondents, who reports that it affords some relief. Lights to be 

 most successful should be placed over vessels of water on which a thin 

 scum of kerosene is floating. 



In any case a careful lookout should be kept for this and other 

 insects which injure the plant by eating its leaves. 



Arsenical spray. — Paris green or other arsenical would, if applied at 

 the outset of the attack, effect the destruction of the larvae, but it has 

 not been ascertained by practical experience whether or not such a 

 spray would destroy the more mature larvae. Owing to their more or 

 less protected manner of working, it would probably not do so effectu- 

 ally. An underspraying is, of course, a necessity. 



This and hand methods are about the only remedies applicable to 

 celer}^ beds and elsewhere out-of-doors. An objection to the use of 

 Paris green on violets and some other greenhouse plants is that the 

 plants have to be syringed every few days for protection against the 

 so-called "red spider," and this would wash away the arsenite. 

 Another is that a poisonous wash could not be used when the plants 

 are in bloom. It might also injure the foliage of certain tender plants. 

 It is better to use some remedy that will at the same time destroy 

 other insects with which the greenhouse may be affected. 



Tobacco as a greenhouse fumig 'ant. — The most widely useful insecti- 

 cide for greenhouse fumigation is tobacco in its various forms. In 

 many instances it is without doubt the cheapest and safest insecticide 

 to use against certain greenhouse insects, particularly plant-lice. Its 

 effectiveness, however, under the best conditions is not great, as it 



