ze and shape of the galls are specific to the majority of gall wasps with about 70% of the known species living in various types of oak trees. Galls occur on nearly all parts of trees including leaves, buds, branches, and roots. Other species of plant where galls are commonly found include eucalyptus, rose or maple trees, as well as many herbs. Frequently, identification a of species of gall forming insect is easier by the shape of the galls produced rather than the insect itself. Some of the more common types of galls caused by the feeding of these insects are discussed below.
Oak artichoke galls develop as a chemically induced distortion of leaf axillary or terminal buds on Pedunculate Oak (Quercus robur) or Sessile Oak (Quercus petraea) trees, caused by the parthenogenetic gall wasp Andricus fecundatrix which lays single eggs within leaf buds using their ovipositor. The larva lives inside a smaller hard casing inside the artichoke and this is released in autumn.
Oak Artichoke Galls. Image Courtesy Rasbak
The galls of the rose gall wasp (Diplolepis rosae) are also distinctive and are known as bedeguars or robin's pincushions. These are found on the shoots of dog roses and have a length of up to five centimeters with red long-haired outgrowths. Inside the galls are several chambers, which may be occupied by larvae.
Robin’s Pincushion on Rose. Image Courtesy of Bjorn Appel
Knopper galls develop as a chemically induced distortion of growing acorns on Pedunculate Oak (Quercus robur (L.)) trees, caused by gall wasps which lay eggs within buds using their ovipositor. The gall thus produced can greatly reduce the fecundity of the oak host, making the gall a potentially more serious threat than those which develop upon leaves, buds, and stems. The large one inch gall growth appears as a mass of green to yellowish-green, ridged, and at first sticky plant tissue on the bud of the oak, that breaks out as the gall between the cup and the acorn. If only a few grubs are developing within, then it may appear only as a group of bland folds. Where several grubs are competing for space the shape may become much more contorted, with several tightly bunched galls.
Kopper Galls. Image Courtesy of saharadesertfox.
Neuroterus numismalis is a gall wasp that forms chemically induced leaf galls on oak trees. It has both bisexual and agamic (parthenogenetic) generations and forms two distinct galls on oak leaves, the Silk button gall and Blister gall. The galls can be very numerous with more than a thousand per leaf. his Silk button spangle gall has a cover of golden hairs that give the impression of silk thread. The 0.3 cm button-shaped galls have a pronounced concavity and sit tightly against the leaf lamina.
Silk Button Galls on Oak. Image Courtesy of Image Courtesy of Beentree.
Neuroterus albipes is a gall wasp that forms chemically induced leaf galls on oak trees which has both bisexual and agamic generations and therefore forms two distinct galls, the Smooth Spangle gall and Schenck's gall. The normally cream colored saucer of the Smooth Spangle gall has a small cone elevated in its centre, a pronounced rim and they are sometimes found almost folded in two. The gall may have steaks of purple, red or other colors through it. Typically found on the lower surface, this gall is found more often on the upper surface than other spangle galls and although often grouped together, the numbers on each leaf are far fewer than in species such as Neuroterus quercusbaccarum. The gall is observed to swell appreciably once it has detached and fallen in late autumn. The gall has also been recorded as green, purple, red or pink.
Smooth Spangle Gall. Image Courtesy of Rosser1954
All bees collect nectar and pollen as their main source of food. One of the distinguishing characteristics of all these families is that their body hairs are profusely branched. This adaptation serves to capture and carry pollen. Worldwide, there are an estimated 20,000 species of bees (Michener, 2000), with approximately 4,000 species native to the United State. The non-native Europ