. Annual report. Entomological Society of Ontario; Insect pests; Insects. 10 All the other consignments of these insects which were received proved to be the cater- pillars of the clover cut-worm (Mamestra trifolii). They appeared in large numbers during the month of August and did considerable damage, particularly in fields of peas, turnips and mangold wurtzel. This insect seldom appears in Canada as a serious pest, nor from the condition of the consignments received by me do T anticipate that we shall suffer from their attacks again next year. Of five lots of caterpillars sent from different
. Annual report. Entomological Society of Ontario; Insect pests; Insects. 10 All the other consignments of these insects which were received proved to be the cater- pillars of the clover cut-worm (Mamestra trifolii). They appeared in large numbers during the month of August and did considerable damage, particularly in fields of peas, turnips and mangold wurtzel. This insect seldom appears in Canada as a serious pest, nor from the condition of the consignments received by me do T anticipate that we shall suffer from their attacks again next year. Of five lots of caterpillars sent from different localities, nearly every specimen was found to be parasitised. One lot of over a dozen caterpillars only gave, instead of moths, specimens of Ophion purgatum, an active and beneficial Ichneumon fly, from the other larva; were reared Tachina flies. A fact which has frequently been observed with regard to these cater- pillars, and one which gives great comfort, is that whenever they -increase largely in numbers they are invariably checked by the appearance of friendly parasitic insects. It must be remembered that all insects are not injurious, but on the other hand that many are very beneficial, preying upon and destroying injurious kinds. These belong to dif- ferent natural orders. Amongst the Hymenoptera we find the Ichneumon flies. The female is, as a rule, provided with a long slender ovipositor, by means of which she inserts her eggs beneath the skin of her victim, or, as in the case of our largest species Thalessa lunator, which has an ovipositor between four and five inches in length, pushes it into the burrow of the woodboring host. The eggs of some are laid upon the outside of the skin and not inserted beneath it. These parasites are some of them as Thalessa external feeders lying alongside of their hosts, they pierce through their skins and suck out the juices, some, and probably most, as the grub of the Ophion above-mentioned, after hatching, lie inside the cavity of
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectinsects, bookyear1872
