. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. 121 It will be noticed by referring" to the table that the greater percent- age of parasites come from the smaller larvae; or, in other words, that the larvae are destroyed before they are half grown and consequently before they have done the greater part of their injury to the plants. HYMENOPTEKOUS PARASITES. Practically all the parasites bred from the young larvae belong to the same species, JficropUtis nigripennis Ashm., of the famil}^ Bra- conid*. This species was first bred in the laboratory from a larv
. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. 121 It will be noticed by referring" to the table that the greater percent- age of parasites come from the smaller larvae; or, in other words, that the larvae are destroyed before they are half grown and consequently before they have done the greater part of their injury to the plants. HYMENOPTEKOUS PARASITES. Practically all the parasites bred from the young larvae belong to the same species, JficropUtis nigripennis Ashm., of the famil}^ Bra- conid*. This species was first bred in the laboratory from a larva collected on tobacco at Paris July 5, 1904, but it was not observed in any numbers until the middle of August, when a large percentage of the boUworms feeding on alfalfa were found to be parasitized b}^ it. Its frequent occurrence on cotton after that time has been referred to. The eggs of the parasite are deposited in larvae which are about 10 or 12 mm. in length, or much more rarely in larger specimens. After it has been stung by the Braconid, the larva continues to feed, but at a much diminished rate, for two or three days. It now becomes very slug- gish and eats th-e involucre of the square or boll in a rather desultory manner, chewing it into small bits, mam^ of which it fails to swailow. These small pieces usually remain webbed to- gether loosely by delicate strands of silk spun by the boll worm, and present quite a characteristic appearance. By the time the parasitic grub is full- grown, the larva lias ceased feeding entirely and is scarcely larger than when first attacked. The Microplitis now bores its way out through the skin of the quiescent bollworm, leaving a large black scar (see PI. XIX, fig. 1) to mark the point of its emergence, which is gen- erally on one side of the body, near the first pair of prolegs. In one case the grub was watched during the act of emerging from the boll- worm. It had protruded the pointed head and was gradually working- its fleshy body
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