The gall's range is computed from the range of all hosts that the gall occurs on. In some cases we have evidence that the gall does not occur across the full range of the hosts and we will remove these places from the range. For undescribed species we will show the expected range based on hosts plus where the galls have been observed.
Created Feb 4, 2026 1:47 PM UTC
•
Last updated Feb 4, 2026 1:47 PM UTC
The comparative morphology of the zoocecidia of Celtis occidentalis
Bertram Wells
(1916)
Pachypsylla sp. (gemma? see next) Figure 4
This gall is a lateral, oval swelling of the stem, generally found near or involving the nodal region. 5-7 mm. long, 2.5-3.5 mm. wide. Color and surface texture that of the normal bark. Predominately monothalamous ; confluent cases occur forming a two-chambered and even a three-chambered gall. Very common on the terminal twigs of the hackberry. Remnants of old galls can be made out on stems 5-10 years old. The galls are commonly torn open by birds to obtain the soft insects within, which spend the winter in the galls. One of these nymphs is shown on the gall (PI. XIX, Fig. 3).
It is not definitely known whether the imagoes from this gall and those from the next, P. gemma, are identical. The nymphs appear to be identical. The galls, however, are distinct, a difference, however, which may be referable to the plant part affected rather than to any specific behavior on the part of the insects respectively. This matter will be explained after P. gemma has been described.
This gall started in a similar manner to that of P. vesiculum, by the larva inducing a cone of tissue to grow over it, burying it in the superficial layer of the young stem. This minute cone early becomes obliterated.
