Page:The Gall Wasp Genus Cynips.pdf/190

184 small, inconspicuously green in color, and so ephemeral that the chances of their collection are much reduced. They are bud galls that appear with the bursting of the leaf buds the first thing in the spring; they reach full size within a few days, and are then so loosely attached to the young, developing stems that they fall to the ground in a heavy wind or at the slightest touch. The larval insects reach full size rapidly and, transforming into adults, emerge within perhaps three weeks after the galls first appear. Emergence thus varies with the season, latitude, and altitude, the limits of our scant records being March 23 further south (at Three Rivers for form ribes) to May 13 further north (at Kelseyville for form atrata). Most of the emergence is probably in April. The males are not rare in our collections and they are probably produced in equal abundance with the females. Oviposition has not been observed, but it must be in the veins of the then young but unfolded leaves, for the agamic galls appear within a month and a half to two months of that time. The bisexual galls shrivel very greatly when collected and dried, and decay very rapidly when moist, the latter being the explanation of our complete failure to find them except in the short season before the maturity of the insect.

The young galls of the agamic forms first appear, at least north of the Sierra Madre, early in the summer; the larvae are mature within a couple of months, and the adults mature at various times from then on, emergence occurring in December or January. It should be noted that in mid-winter, in most of the areas involved, freezing temperatures are rare (varieties echinus and douglasii), while the colder days and snow storms of other parts of the region are intermingled with warm days when emerging insects might easily become active.

The insects and the galls of the bisexual and agamic forms here described have not hitherto been recognized as successive generations, for they are superficially quite distinct. They are not yet connected by the experimental data to which our conclusions must always be subject; but a closer examination shows so many points of similarity and so much confirmatory host, distribution, and life history data that we may be justified in our present interpretation.

In the first place, the bisexual insects clearly belong to the genus Cynips and to the subgenus Antron.