Disholcaspis cinerosa (agamic)

Disholcaspis cinerosa (sexgen)

Disholcaspis cinerosa
Asexual generation

The asexual generation develops within mealy-oak galls on branches and branch lets of host trees (figure 1). These spherically shaped galls are familiar to people who live in cities where live oaks commonly are planted as ornamentals. Galls range from 1/8 to 1 inch in diameter and are first noticed in late summer or early fall, depending on locality. When first formed, they are small, light pink to pinkish brown and the internal tissue is soft (figures 1 and 3).

From late summer to late fall (figure 4) developing Disholcaspis larvae eat plant tissues within galls. From August to mid-October, internal gall tissue is yellow-green and moist (figure 3), while during late October and November the tissue turns brown and begins to dry (figure 4). During November, pupation occurs and shortly thereafter transformation to the adult stage takes place. During December and the first part of January, adults emerge by chewing holes at gall bases (figure 1). 

During the first winter, recently abandoned spherical galls begin to weather and in the process change from pink to grey and become dry and hard (figure 1). If left undisturbed, they may persist on host trees for several years. In essence, grey galls are inactive structures that serve to remind one of a past event. They actually assume a nonliving status about 1 month (November) before adults begin emerging from the galls.

Range: Gall-infested live oak trees occur throughout Texas in natural and planted situations. The gall wasp also is reported from the same host in certain parts of Mexico and from western Louisiana. 

Disholcaspis cinerosa
Sexual generation

Females of the asexual generation lay their eggs in swollen leaf buds. These eggs hatch in early spring as leaf buds begin to open. Resulting larvae develop quickly in new leaf tissue, and in the process they induce the formation of a second type of gall. This new growth is beige and resembles a kernel of wheat in size and shape (figure 5). Larvae, pupae and adults complete development in a few weeks within these small, obscure galls. The sexual generation differs from the asexual generation not only in gall type but also in that the spring galls produce adults of both sexes. Sexual generation adults are about 1/3 the size of the asexual generation adults (figure 2). Immediately after emergence, male and female wasps mate; males then die. Mated females may live up to a week during which time each individual deposits about 15 eggs in the branches of live oak.

The eggs pass through a 3- to 5-month dormant period. After this period, larvae hatch and begin development in certain outer branch tissues, which leads to formation of pink spherical galls (figure 1). Thus, the annual cycle of Disholcaspis is completed.

Range: Gall-infested live oak trees occur throughout Texas in natural and planted situations. The gall wasp also is reported from the same host in certain parts of Mexico and from western Louisiana. 

The Mealy Oak Gall on Ornamental Live Oak in Texas