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Psyche 
[Vol. 90 
turn, these nonassociated arthropods are preyed upon by the pre- 
daceous ants and spiders. Biochemical analyses of nectary secretions 
in California bracken indicate the presence of relatively large con- 
centrations of glucose and fructose, minute concentrations of 
sucrose and maltose (Irene Baker and Peter Atsatt, pers. comm.), 
and an undetermined number of free amino acids. 
By mid-May, when the primary nectaries at the axils of the pinnae 
are secreting microliters of “nectar” daily, the thiaminase activity is 
declining rapidly and the cyanogenic glucoside may or may not be 
offering protection. In addition, the levels of tannins and silicate are 
still at low levels, while proteins are at optimal level (Lawton, 1976). 
Thus, the crozier stage of bracken may at once present a nutritious 
stage to attack as well as a “loophole” in the biochemical arsenal. 
The potential for attack at this time by nonadapted polyphagous 
herbivores is great, and we have established that several nonadapted 
herbivores will feed readily on bracken croziers without ill effect. 
These include the gypsy moth, Porthetria dispar (L.) (Lepidoptera: 
Liparidae), the large milkweed bug, Oncopeltus fasciatus (Dallas) 
(Hemiptera: Lygaeidae), the common rose chafer, Macrodactylus 
subspinosus (Fabricius) (Coleoptera: Scarabaeidae), and a large 
tropical cockroach, Blaberus giganteus (L.) (Orthoptera: Blaberi- 
dae). 
Many croziers are not attacked because their actively secreting 
nectaries are quickly located by at least five species of ants in Michi- 
gan: Formica subsericea Say, Formica obscuriventris Mayr, For- 
mica pallidefulva nitidiventris Emery, Camponotus pennsylvanicus 
(De Geer), and Camponotus nearcticus Emery. Camponotus pen- 
nsylvanicus, Formica obscuriventris, and Formica subsericea in 
particular defend the nectaries and the developing crozier by patrol- 
ling the plant in a very systematic manner. An ant patrol typically 
begins after both primary nectaries at the base of the pinnae are 
antennated and sampled with the mouthparts for 1-3 minutes. The 
ant then proceeds up and down each pinna, investigating the pin- 
nules and attenating the smaller nectaries even though these rarely 
secrete visible quantities of nectar. A single patrol, covering the 
entire frond, may last from 2 to 15 minutes, depending upon the size 
of the crozier and the length of the time spent at each nectary. 
One ant, or several ants from the same colony may patrol a given 
crozier, but all other “intruding” arthropods are bitten and stung 
