488 



Forest trees suffered chiefly from a species of Chorines found on 

 Douglas fir in the New Forest and recognised as being identical with 

 C. cooleyi var. loweni occurring in North America. In the United 

 States the alternative food-plants are certain spruces, and in England 

 the Sitka spruce (Picea sitchensis). The attack on the latter tree is 

 almost entirely confined to the lower branches, and it has been remarked 

 that if it were possible to remove or even spray the lower branches of 

 spruce in June and July the pest might easily be controlled. Minor 

 pests of forest trees include willow-scale [Chionaspis salicis], ash-bark 

 beetle {Hylesinus fmxini), hazel gall-mite [Eriophyes aveUanae], poplar 

 longicorn [Sapenia] and wood- wasps [Sir ex spp.]. 



Strickland (E. H.). Parasites of the Pale Western Cutworm in 



Alberta.— Cawai/. Ent., Giielph, liii, no. 5, May 1921, pp. 97-100. 

 [Received 8th August 1921.] 



Since 1911, Porosagrolis orthogonia, Morr., has been the most des- 

 tructive pest of grain crops in Alberta and in parts of south-western 

 Saskatchewan, the damage in some years amounting to over /^200,000. 

 No remedial measure has proved successful when applied to large 

 infested areas. The winter is passed in the egg-stage, which is very 

 resistant to frost, and the larvae remain underground, where they are 

 protected from predators such as Calosoma frigidum, Klg., and 

 Ammophila spp., and are unaffected by irrigation. 



Parasites however are important, and the severity of outbreaks 

 can usually be gauged in advance by a study of the parasite conditions 

 of the previous year. Species that have been bred in considerable 

 numbers are the Hymenopteron, Meteor us dimidiatus, Cress., which 

 has two generations in a year, the larvae hibernating in overwintering 

 cutworms such as Euxoa tristicula, Morr. The adults emerge in May 

 and attack P. orthogonia and other Noctuids. The female lays about 

 twelve eggs in each host, and adults of the second generation usually 

 emerge in Jul3^ This Braconid has also been bred from Sidemia 

 devastatrix, Brace, a cutworm that has never been recorded as coming 

 to the surface. 



Gonia capitata, DeG., and at least two allied species of Tachinid, 

 have one generation a year, hibernate as pupae, and emerge as adults 

 in May. The eggs are laid in numbers on vegetation, and hatch when 

 eaten by cutworms. The larvae mature at about the time that the 

 host pupates, and hibernate as pupae either in the soil or in the dead 

 larva or pupa of the host. The selection of vegetation by the fly and 

 the position of eggs on the selected plants are important factors that 

 affect the value of this parasite. The most abundant oviposition 

 has been found on blue-joint grass {Agropyron smithi), less frequently 

 on other native grasses and imported Gramineae and grain crops. 

 As P. orthogonia does not feed readily on blue-joint and G. capitata 

 does not apparently prefer the lower portion of the plants for oviposi- 

 tion, the high percentage of parasitism is rather remarkable. Periods 

 of drought are apparently beneficial to the parasite, necessitating 

 more abundant oviposition on the fewer available plants. Bonneta 

 comta, Wied., is a Tachinid parasite about which little is known. 

 The adult appears in July and August and is larviparous. It has 

 probably two generations a year, though it has not been bred from 

 overwintering cutworms. Its habit in the selection of plants for 

 oviposition is probably similar to that of G. capitata, P. orthogonia 



