568 IOWA DEPARTMENT OF AGRICULTURE 



unruly but yet are likely to remain alive and furnish fresh food for the 

 waspling. With them is placed a single egg, then the mother leaves. 

 Some species of wasp mothers never see their offspring, while others 

 return at intervals to bring fresh food. 



One wonderful thread-waisted creature, the sand-loving Ammophila, 

 is said "to take a small square pebble in her mandibles to tamp the 

 filled-in shaft in which she has placed her larder and laid her egg, so 

 that it may appear undisturbed like the surrounding soil. Man has been 

 defined as the tool-using animal, but here we have the remarkable ex- 

 ample of a wasp that uses tools. 



But, you ask, what is the practical import of all this? Well, the 

 grown-up wasp departs from its early dietary training and acquires a 

 taste for the sweets from flowers. The flower is its dining table, not its 

 field of labor. It is the Nimrod of the insect world, and devotes its 

 busy hours to the chase, whereby it satisfies the needs of the home. 

 Still it must tarry at the flower bed to meet its own personal needs. 



Since it does visit flowers in its blustering sort of way, it is bound 

 to carry pollen. For several reasons it is a less important agent of 

 pollination than is the bee. Its season is shorter,— very few being 

 seen on fruit blossoms in spring and on the last lingering dandelions and 

 asters in fall; then because of the hunting habit that we have men- 

 tioned the wasp has less time during the day to spend on the flower 

 than has the bee; it has no pollen-baskets and does not intentionally 

 gather pollen; it is generally less hairy, and its hairs are simple, not 

 branching and feather-like as are those of the bee, — the wasp's body under 

 the microscope appears as a field covered with telegraph poles and not 

 as a miniature forest as does that of the bee. But most of our showy 

 fiowers have sticky pollen-grains, which will readily adhere upon con- 

 tact with the hairs of the wasp. A medium-sized wasp, Cerceris clypeata, 

 which we collected from golden rod, was found to have on its body two 

 thousand pollen grains of several different kinds. 



Some flowers are preeminently wasp flowers. Possibly their nectar 

 is not apreciated by bees. Among such we might mention the dog- 

 banes and the green milkweed. On a plot of this milkweed four feet 

 square on July 22 there was seen but one honey bee during the entire 

 day, while there was an average of fifteen wasps on hand all day long. 

 The dogbanes and milkweeds have a treacherous way of trapping small 

 insects, and it may be that some of our wasp visitors are really trappers 

 and are in quest of the insects that the flowers catch. But the majority 

 are undoubtedly after mectar, for their insect food is of a type wholly un- 

 likely to be found on milkweed blossoms. Now the pollen of the milk- 

 weed clings together in a peculiar way, and is jerked out by the foot of 

 the visiting insect. Fig. (4) Wasps taken from milkweed usually have 

 one or more of these pollen masses on their feet, hence it would appear 

 that they play some part in the pollination of this plant. 



Passing on to the true bees, skilled gatherers of pollen and honey, 

 we find two families, the short-tongued and the long-tongued bees. This 

 distinction is an important one, for, as we shall see, it determines what 

 flowers the bees may visit. The short-tongued bees are all solitary, each 



