o 



62 THK UAJNAUIAN KM'H iMOLt>Glb'J . 



A NEW RF/rixNIA ATIACKING AUS IRIAN PINE. 



BY A. COSENS, JAMIESON AVE. C< )LI-F.GIATE INSTITUIE, 'lORONTO. 



Reti'iia Ajistriana. n. sp.-— The Austrian Pine ( Piiucs laricio 

 Austriaca) in the vicinity of Toronto is badly infested by the larvce of a 

 moth which is apparently an undescribed species of the genus Retinia. It 

 resembles in certain particulars the form Retniia Comstockiana. This 

 species was described in the Canadian Entomologist of Aug., 1879, by 

 Prof. C. H. Fernald, State College, Orono, Me. The specimens, however, 

 were obtained at Ithdca. N. Y., where they were found boring in the small 

 branches of Piiius rigida. 



The Toronto species burrows in tiie cortical layer of the Austrian 

 Pine. The tunnels formed pierce the resin ducts, the gum exudes and 

 hardens into masses on the baik of ihe trees. The point of attack appears 

 to be usually beneath the origin of a iirnb. The larvje work on a more or 

 less horizontal plane, and in consequence of this the trees have been, in 

 some cases, almost girdled. 



This form also resembles R. Comstockiana in its life-history. I'he 

 larva when mature burrows into the lump of resin that has hardened over 

 the entrance to its tunnel, and there pupates. The thin covering of gum 

 left over the burrow is broken through by the imago when it emerges. 



Hie larva prepares its burrow in the lump of resin in a very charac- 

 teristic manner. Two larv^ were placed on a mass of the gum, and in a 

 remarkably short time they had sheltered themselves in it. Their mode 

 of operation was as follov/3 : Selecting an accidental crevice in the resin, 

 they crawled into it, and immediately began to weave threads of silk 

 across the opening. The burrow was then enlarged by biting off pieces of 

 the gum. The little masses broken off were disposed of by being forced 

 against the covering of silk threads until they adhered to it. This very 

 soon so effectually closed the burrow as to make it a matter of some 



difficulty to find its location. This closing of the burrow, when done 

 under natural conditions, may be a means of preventing further exudation 

 of resin. In all the cases examined the tunnel appeared to be quite open 

 for some distance behind the pupa. 



In High Park, Toronto, nearly all the Austrian Pines are infested. 

 In all cases the trees are being materially iijured, and in son;e cases have 

 been killed. Trees of the same species in other /Foronto localities have 

 been found to be infested. 



'I'he ravages of this moth are checked by parasitic agency to a certain 

 extent, as an Ichneumon Fly emerged from a mass of resin collected by 

 the writer. 



November, 1906 



