INSECTS IN RELATION TO PLANTS 



207 



The bogus Yucca moth (Prodoxus quinqucpunctella) closely resembles 

 and associates with Pronuba but oviposits in the flower stalks of Yucca 

 and has none of the special adaptive structures found in Pronuba. 



As regards floral adaptations, these examples are sufficient for present 

 purposes; many others have been described by the botanist; in fact, the 

 adaptations for cross pollination by insects are as varied as the flowers 

 themselves. 



Insect Pollenizers. The great majority of entomophilous flowers 

 are pollenized by bees of various kinds; the apple, pear, blackberry, 

 raspberry and many other rosaceous plants depend chiefly upon the 

 honey bee, while clover cannot set seed without the aid of bumble bees 

 or honey bees, assisted possibly by 

 butterflies. Lilies and orchids fre- 

 quently employ butterflies and 

 moths, as well as bees, and the 

 milkweed is adapted in a remark- 

 able manner for pollination by 

 butterflies, moths and some wasps, 

 as was described. Honeysuckle, 

 lilac, azalea, tobacco, Petunia, 

 Datura and many other strongly 

 scented and conspicuous nocturnal 

 flowers attract for their own uses 

 the long-tonged sphinx moths (Fig. 

 260); the evening primrose, like 

 milkweed, is a favorite of noctuid 

 moths. Umbelliferous plants are 

 pollenized chiefly by various flies, 



but also by bees and wasps. Pond lilies, golden rod and some other flowers 

 are pollenized largely by beetles, though the flowers exhibit no special 

 modifications in relation to these particular insects. It is noteworthy 

 that pollination is performed only by the more highly organized insects, 

 the bees heading the list. 



Of all the insects that haunt the same flower, it frequently happens 

 that only a few are of any use to the flower itself; many come for pollen 

 only; many secure the nectar illegitimately; thus bumble bees puncture 

 the nectaries of columbine, snapdragon and trumpet creeper from the 

 outside, and wasps of the genus Odynerus cut through the corolla of 

 Pentestemon Icevigatus, making a hole opposite each nectary; then there 

 are the many insects that devour the floral organs, and the insects which 



FIG. 260. PliJc^ctlionlins sexta visiting flower 

 of Petunia. Reduced. 



