. Entomology : with special reference to its biological and economic aspects. wer without the help of a little whitetineid moth, Pronuba yuccasella, the female of which pollen-izes the flower and lays eggs among the ovules, that her larvae may feed upon theyoung seeds. Whilethe male has no un-usual structural pecu-liarities, the female isadapted for her specialwork by modificationswhich are u n i q u ea m o n g Lepidoptera,namely, a pair of pre-hensile and spinousmaxillary tentacles (Fig. 256, A) and along protrusible ovi-positor {B) whichcombines in itself thefunctions of a lanceand a saw. Th
. Entomology : with special reference to its biological and economic aspects. wer without the help of a little whitetineid moth, Pronuba yuccasella, the female of which pollen-izes the flower and lays eggs among the ovules, that her larvae may feed upon theyoung seeds. Whilethe male has no un-usual structural pecu-liarities, the female isadapted for her specialwork by modificationswhich are u n i q u ea m o n g Lepidoptera,namely, a pair of pre-hensile and spinousmaxillary tentacles (Fig. 256, A) and along protrusible ovi-positor {B) whichcombines in itself thefunctions of a lanceand a saw. The female begins to work soon after dark, and will con-tinue her operations even in the light of a lantern. Clingingto a stamen (Fig. 257) she scrapes off pollen with her palpiand shapes it into a pellet by using the front legs. xA-ftergathering pollen from several flowers she flies to anotherflower, as a rule, thrusts her long flexible ovipositor into theovary (Fig. 258) and lays a slender egg alongside seven oreight of the ovules. After laying one or more eggs she ascends. Pronuba yuccasella. A, maxillary tentacleand palpus; B, ovipositor.—After Riley. Fig-ures 256-258 are republished from the ThirdReport of the Missouri Botanical Garden, bypermission. INSECTS IN RELATION TO PLANTS 265 the pistil and actually thrusts pollen into the stigmatic tube andpushes it in firmly. The o\ules developinto seeds, some of which are consumedby the larva;, though plenty are left toperpetuate the plant itself. Three speciesof Promiha are known, each restrictedto particular species of Yucca. Rileysays that Yucca never produces seedwhere Prouuba does not occur or whereshe is excluded artificially, and thatartificial pollination is rarely so success-ful as the normal method. Why does the insect do this? The lit-tle nectar secreted at the base of the pistilappears to be of no consecjuence, at pres-ent, and the stigmatic fluid is not necta-rian; indeed, the tongue of Prouuba, usedin clinging to t
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