Family Psyllidae 
Jumping Plantlice 
Jumping plantlice or psyllids are very small, about 2 to 5 mm long, and look very 
much like minature cicadas. There is also some resemblance to winged aphids but 
psyllids differ in having stouter legs, with the hind pair adapted to jumping. The 
nymphs of certain species which secrete large quantities of wax resemble woolly 
aphids. The adults are very active and jump or fly when disturbed. 
Psyllids fall into two species groups: (1) the leaf gall makers, and (2) the woody 
gall makers. Adults of the leaf-feeding forms emerge from galls in the fall: the 
wood-feeding forms emerge in spring. Leaf gall makers are further subdivided into 
two groups, blister gall makers and nipple gall makers. 
Pachypsylla celtidisvesicula Riley, the blistergall psyllid, forms a small, mono- 
thalamous (one psyllid per gall) blister gall. It is believed to occur throughout the 
range of hackberry in the United States and is the most abundant of the hackberry 
psyllids. Fifty or more may infest a single leaf. Adults often become a household 
nuisance when thousands accumulate on screens in the autumn before hibernating. 
Two undescribed species of blistergall psyllids occur on sugarberry and netleaf 
hackberry. 
Pachypsylla celtidisastericus Riley, the hackberry stargall, produces a gall that 
closely resembles the blistergall formed by the blistergall psyllid, except that it has 
starlike growth on the lower side of the leaf. It can occur on all hackberry tree 
species except Celtis occidentalis L. | 
The hackberry nipplegall maker, P. celtidismamma (Riley), is perhaps the best 
known hackberry psyllid. It is found only on C. occidentalis. There are other 
nipplegall makers on the other four species of hackberry trees, but they are not this 
species. It is monothalamous, although at times it may appear to be polythalamous 
because as many as seven galls of another psyllid, P. celtidisvesicula, may be 
incorporated into a single nipplegall of P. ce/tidismamma (890). Like the blistergall 
psyllid, adults cluster on screens during the fall. The nipplegall psyllid may 
disfigure leaves when infestations are heavy (///2). 
Pachypsylla celtidisgemma Riley, the budgall psyllid, occurs throughout the 
range of hackberry trees in the United States, and may become a pest when 
populations are high. Adults appear during the latter part of June in the New York 
City area and lay their eggs on the young leaves. Young nymphs enter the buds and 
initiate gall formation. The polythalamous galls contain several nymphs, each in its 
own chamber. The winter is passed as a fifth nymphal instar in the gall (/243). 
Pachypsylla venusta (Osten Sacken), the petiolegall psyllid, is the largest of the 
hackberry psyllids, and it forms the largest galls. The galls are polythalamous and 
usually contain 6 cells, although there may be as many as 30. These galls may 
persist on the trees for several years and seriously damage their appearance. 
Distribution of the species is mostly limited to below the 40th parallel. 
Pachypsylla celtidisinteneris Mally forms small, inconspicuous, monothalamous 
galls under the bark of hackberry twigs. 
Several other species in the genus Psy/la feed on various trees, shrubs, and 
ornamentals, and produce large quantities of honeydew that drips and covers their 
hosts. A black mold growing in this material often makes infested plants look less 
healthy than they are. 
The boxwood psylud, Psyl/a buxi (L.), attacks American and English varieties 
of boxwood and probably occurs wherever they grow. The adult is greenish and has 
transparent wings; nymphs are gray-green and covered with a white cottony or 
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