GALLS CAUSED BY GALL-WASPS 
27 
representing nearly all the orders, have been obtained from 
a single gall! 
The cynipidous galls may be conveniently considered 
under two headings. 
I. GALLS ON PLANTS OTHER THAN OAK 
The causers of these belong to five genera— Aulacidea , 
Aulax , Diastrophus , and Rhodites. 
Aulacidea hieracii attacks the stem and root of the Common 
Hawkweed, Yellow Toadflax, and Couch-grass; the larvae 
give rise to longitudinal or rounded swellings. In the last 
named the distortion is usually slight. Several larvae occupy 
a cell. Galls caused by certain species of Aulax are very 
familiar objects. Three of them are shown in our plates. 
The larvae of Aulax hypochaeridis give rise to elongated and 
fusiform (rarely rounded) swellings on the stem of the Long- 
rooted Cat’s-ear (Plate XXIX., Fig. 1). The petioles are 
sometimes attacked, and not infrequently the whole plant 
is deformed. The galled part is yellowish-green or brown 
at maturity. The gall is plurilocular ; each cell contains a 
yellowish-white larva. Fig. 3 depicts a section, natural size. 
The larvae pupate in the gall, and the wasps appear in 
spring. Plate XXIX., Fig. 4, shows an imago, magnified. 
Equally common galls arise on the leaves and stems 
of the Ground Ivy (Plate XXIX., Fig. 5) when attacked by 
Aulax gltchomae. They vary in size from a pea to a large 
marble, are yellowish-green at first, becoming suffused with 
red or purple at maturity, and are covered with long white 
hairs. These galls are usually solitary ; sometimes two or 
three coalesce ; a section of such is shown at Fig. 7. The 
larva (Fig. 8) pupates in the gall, the imago (Fig. 9) 
appearing the following April. In the growing state the 
gall is soft and sappy; at maturity the interior is dry and 
fibrous, the larva being encysted in a remarkably hard 
inner gall. The larvae are attacked by several parasites. 
Reaumur * remarked that these galls were eaten by the 
* “ Mem.,” iii., p. 416. 
