GALLS CAUSED BY GALL- WASPS 37 



reddish at first ; Fig. 6 gives a magnified view of a growing 

 one, and Fig. 5 a section of an adult. They arrive at 

 maturity (Fig. 4, seven galls opposite to letter a) in 

 September, become detached from the withering leaf, and 

 fall to the ground. After falling, the gall loses its umbonate 

 appearance and becomes round; the larva continues to 

 grow in it, pupates in March, and the wasp, Neuroterus 

 lenticulans (Fig. 7), appears in April, a minute insect about 

 2-5 or 3 mm. long. This gall was as abundant in 1904 as 

 the alternate form. On three leaves from a sapling Oak 

 at Haslemere I counted 286, 379, and 326 galls, an average 

 of 330 for each leaf. 



Fig. 8, d, on Plate V., depicts the oval yellowish gall of 

 Neuroterus alhipes. It appears in May; the wasp emerges 

 and attacks the leaves in June, and the smooth spangle 

 gall appears in July. This gall is cup-shaped (Plate V. 9,/; 

 a magnified section is shown at Fig. 10). It matures in 

 September, falls to the ground, and the wasp, Neuroterus 

 laeviusculus, appears the following March. 



Fig. 8, c, on the same plate, shows two blister galls caused 

 by the presence of the larvae of Neuroterus vesicator. These 

 galls are pale green, and more or less rounded, projecting 

 slightly from both surfaces of the leaf. On the superior 

 surface there is a small raised point from which striae 

 radiate to the margin (see magnified section. Fig. 11). 

 They appear in May, and the wasps emerge in June, to 

 prick the under surface of leaves and give rise to the 

 beautiful little silk-button spangle galls (Plate V., Fig. 9, e ; 

 Fig. 12 is a magnified section, and Fig. 13 an enlarged view 

 of a gall), from which Neuroterus numismatis emerge in April, 

 and attack the leaf buds, giving rise to blister galls. The 

 silk-button gall was remarkably abundant in 1904. Three 

 leaves bore 1,741 galls, in the proportion of 502, 558, and 

 681. To appreciate fully the beauty of this gall it should 

 be examined with a binocular microscope, using a 2-inch 

 objective. 



Fig. 14 on Plate V. depicts two of the hairy Pea galls 



