Of all the biologists who have devoted themselves to the habits of insects, Ferton is surely one of the most precise. Sagacious and penetrating, he submits his observed facts to a very severe analysis and reports them in conservative terms. He is a sure and perspicacious guide. ' 1 After more than a quarter of a century of observations on Hymenoptera," he writes in his most recent work, "I have only very rarely seen acts of intellect, and yet all did not act with only a modification of instinct." One would think that he agreed with Fabre, but the latter believed in the immobility of instincts, while Ferton concludes from his studies that they are modified slowly, very slowly, '1 this variability coming to be of the same kind as the structure of the insect."

1 Monsieur Labitte has shown me that Ateuchus does not always do this, but this is no contradiction of Fabre.

It is in the solitary bees of the genus Osmia that he noted the most numerous and the greatest variations in habit. It is known that the group including Osmia papaveris have the habit of lining their cells with the petals of certain flowers, each species choosing for this purpose a preferred plant. Osmia lanosa and 0. papaveris confine themselves to the red petals of the corn poppy, so far as possible. In Corsica, Ferton has seen the first-named species take the yellow petals of Glaucium luteum and of Sisymbrium officinale and the blue petals of Matthiola tricuspidata and the white corolla of Convolvulus sepium when a drought deprived it of the poppy; and at Mont-louis, where this latter flower is lacking, he has noted that Osmia papaveris uses the musky mallow. Ferton adds, after Buttel-Reepen, that in Pomerania the same species gathers the petals of the corn-flower. He notes in another place that Osmia perezi substitutes mallow for the morning-glory, and that Osmia cristata substitutes the tree mallow for the common mallow.

Raphiglossa zethoides of the family Eumenidce is a solitary wasp which nests in broken twigs, in which it encloses paralyzed beetle larvae with an earthy or sandy cement. Ferton says :

At La Calle one of these wasps collected grains of sand and carried them to a vertical stem of Arundo [a reed], a clump of which grew a few steps away. The stem chosen was broken about fifty centimeters above the ground, and the break, being very near the first node, left above it a canal only one centimeter long. So the wasp pierced a hole in the reed four centimeters below the node to effect her entry into the stem between the nodes, and in there she made her nest.

The free end of a broken stem is the spot usually chosen for the nest by Hymenoptera which work in this way, but the free end in this instance being too short, the wasp departed from its usual custom and chose the cavity of the following internode and pierced it from the outside.