BEETLES AND FLOWERS 



Many beetles pass their entire life on a single plant species. 

 The larvae of Donacia piscatrix mine in the leaves and stems of 

 the yellow water-lily, while the adult beetles flourish within 

 the floating flowers; another species of Donacia attaclics its 

 cocoons to the base of the stems of the marsh-marigold, and 

 when the flowers open they emerge and climl) the stems and 11 \e 

 in plenty, half bin-ied among the stamens; the larvie of the fa- 

 miliar asparagus-beetle eats the leaves of the cultivated aspara- 

 gus, and the beetles visit the flowers. (Fig. 90, No. 7.) 



The blue-flag beetle {Mononychus vulpeculus) passes its 

 entire life on the blue flag, and is most common during the 

 blooming-time of the flowers. (Fig. 91.) It is inactive in the 

 bright sunshine, says Needham, and will dodge around the 

 base of a flower like a squirrel around the base of a branch 

 when a hand approaches, but will rarely fly. "With its beak 

 it sinks a shaft in the nectariferous tissue, nibbles a little, makes 

 another hole, and another, and another, until the nectar is left 

 flowing from many punctures, attracting swarms of insects of 

 all sorts." In one instance while the weevil was gnawing a 

 hole, there were three flies facing it and another on its back, 

 "crowding one another like pigs around a trough." The eggs 

 are laid in the seed-capsule, the larva' feed on the young ovules 

 until they undergo their transformation into beetles, and 

 finally in the fall the bursting of the capsule sets free both the 

 weevils and the seeds. (Fig. 90, No. 8.) 



The blister-beetles also restrict their visits chiefly to one 

 kind of flower; for instance, an oblong, dull-black species 

 (Epicaida pennsylvanica) is much more commonly found on 

 the flowers of the goldenrod than elsewhere. At times the 

 blister-beetles appear suddenly by bushels and destroy in a 

 few days large patches of potatoes and tomatoes. The larvae 

 are brood-parasites on bees, grasshoppers, and other insects. 



18.5 



