



FK;. 259. A wasp, Sphex ichneu- 

 mon e a, with pollinia of milkweed 

 attached to its legs. Slightly enlarged. 



tincid moth. l'ninh,i \'H w.sr//,/, the female of whi< h polleiii/.r- tin- 1 



and I aiming the ovule-, lli;it her l,i r\ ;c may l< rd upon the \ 



While tin- male ha> no unusual IT*] peculiarities, tin- 



female is adapted t'nr her speeial work 



by modifications which are unique 



amonu; Lcpidoptcra. namely, a pair 



of prehensile and spinous maxillary 



"tentach :. 260, A) and a long 



prolrusible ovipositor ( /*) which com- 



iiines in itself the functions of a lance 



and a saw. 



The female begins to work soon 



after dark, and will continue her opera- 

 tions even in the light of a lantern. 



Clinging to a stamen (Fig. 261) she 



scrapes off pollen with her palpi and 



shapes it into a pellet by using the front legs. After gathering pollen 



from several flowers she flies to another flower, as a rule, thrusts her 



long flexible ovipositor into the ovary (Fig. 262) and lays a slender egg 



alongside seven or eight of 

 the ovules. After laying one 

 or more eggs she ascends the 

 pistil and actually thrusts 

 pollen into the stigmatic tube 

 and pushes it in firmly. The 

 ovules develop into seeds, 

 some of which are consumed 

 by the larvae, though plenty 

 are left to perpetuate the 

 plant itself. Three sp< 

 of Pronuba are "known, each 

 restricted to particular 

 species of Yucca. Riley 

 that Yucca never produces 

 seed where Pronulhi does not 

 occur or where she is excluded 

 artificially, and that artificial 

 pollination is rarely so suc- 



FIG. 260. Pronuba yuccasella. A, maxillary 

 tentacle and palpus; B, ovipositor. After RILEY. 

 Figures 260-262 are republished from the Third 

 Report of the Missouri Botanical Garden, by 

 permission. 



cessful as the normal method. 

 Why does the insect do this? 



The little nectar secreted at the base 



