54 PROTECTION OF PLANTS — 1922-23 



they may be frequently seen passing backwards and forwards from a vegetable 

 seed plantation to the leaves of neighboring currant bushes. Many of the 

 species noted, furthermore, were aphidaphagous, — their larvae living among 

 the colonies of aphids — and adults passed quite readily from the blossoms of 

 plants to colonies of aphids on the twigs of apple or on the leaves of cabbages . 



The food of Syrphids consists primarily of pollen grains, although they 

 seek nectar to a considerable extent. The Muscids, likewise, seek nectar 

 and pollen and the vestiture of these flies is sufficiently long and dense to permit 

 the ready carrying of pollen grains. However, it is my belief that pollination 

 is more usually affected through the moath parts. Their habits of blossom 

 visitation are like the Syrphid flies — somewhat spasmodic. Soldier flies or 

 the Stratiomyiid ce are strictly fiowerloving insects and many species may be 

 taken on the blossoms of vegetables. The size of individual species varies 

 considerably as do their powers of flight. They are probably of more impor- 

 tance than the two families already mentioned as plant pollinators. The 

 Bee flies or Bomhyliidce are usually heavily clothed with a vestiture similar to 

 that of bumble bees. Their hairs are long and rigid and project straight out 

 from the body. Their mouth parts, however, are extended and this fact does 

 not force them to burrow deeply into the blossoms in order to obtain nectar. 

 They are erratic on flight and frequently dart considerable distances; their 

 habits are most interesting. It is n3t unusual to see them hover over a blossom 

 and after extracting the food they require, dart perhaps ten or fifteen or 

 more yards before they visit the next flower. Pollination with these insects 

 is doubtless purely accidental but their remarkable habits in flight doubtless 

 place them in the forefront of local pollinating agencies. The Sarcophagids 

 Dexiids and Tachinids are also of importance as pollen carriers but their 

 influence is purely local and other flies such as Therevids, Dolichopodids, 

 Anthomyiids, Ortalids and Conopids are not great factors. Their legs and 

 bodies are not heavily clothed with hairs and while they may carry pollen , 

 their influence is practically negligible. Among the Hymenoptera the honey 

 bee, the bumble bee, solitary bees and wasps rank very high. 



It will not be necessary to detail the structure of these insects demonstra- 

 ting their effectiveness as pollen carriers. That subject has been dealt with 

 extensively on many occasions. Among beetles we find many species that 

 feed on pollen. They do not move rapidly from plant to plant except possibly 

 in the case of the Cerambycids. Usually beetles found in the seed heads 

 will remain on the same head for hours on end and naturally are considerable 

 factors in the carrjdng of pollen from blossom to blossom in closely compacted 

 seed heads. The roughened portions of their body, the small projections, the 

 minute hairs, enable pollen to be transferred form place to place. With these 

 few remarks I will close the subject. 



