Occasional insect associates of insectivorous plants

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In addition to the regular—often obligatory—associates of insectivorous plants, the occasional presence of other insect species has been noted from time to time. Often these have little or no relation to the special structure of these plants; by more prolonged observation, a few of them might have proven a status of regular association, even with structural or behavioral adjustments to those dangerous habitats. Some of these occasional associates, or those given less conclusive study, are recorded below.

Feeding on the plant substance

The pitchers of the Sarraceniaceae, more especially before they have reached full development and are of soft and tender texture, are occasionally observed to be fed upon, exteriorly, by sundry lepidopterous larvae. Reared to adult, most of these have proved to be Tortricids with known habits indicating acceptance of a wide range of food plants. Sometimes on young pitchers, the feeding is extensive and includes the extension of silken webs into the cavity of the pitcher—noted especially in minor—but also sometimes in other species, and in Darlingtonia. See also Archips parallela Rob.

Less frequently, Noctuid larvae attack the pitchers or other portions of these plants. For example at Whitings, NJ, May 23, 1920, a green larva was found eating the unripe seed vessels of S. purpurea; on this food, it completed larval growth, entered the ground for pupation on June 16, and emerged as a moth Amphipyra pyramidoides Gn., on July 19.

One insect species, with more complete knowledge, may prove to be a true "pitcher plant insect" [and] should be the object of further [re]search. It is a Geometrid whose larvae, by coloration and habit, seem most possibly adapted to association with Darlingtonia. In live plant material sent [to] me by Heller, 1915, from the Mt. Eddy region, these larvae were present in small numbers, feeding on the outside of the expanded hoods of Darlingtonia, and assuming a resting position on the fishtail appendages. This (or other similar larvae) was found also at Keddie, Plumas Co., in 1918; but from both localities, efforts to rear adults failed.

Occupying pitchers, but not feeding on them or captured prey

Leaf-cutter bees (from S. minor in Summerville, SC), [as well as] paper-wasps (Polistes, from S. sledgei in Biloxi, MS), occasionally build their nests in the hoods and tubes of pitcher plants. More frequently than these, the utilization of pitchers, [typically] old pitchers of pupurea, as shelters or retreats by Lycosid spiders carrying or guarding silken egg sacks; often they partly close the orifice of the pitcher with strands of strong silk.

Spiders are of very frequent occurrence in the flowers of Sarracenia, and so generally in those of Darlingtonia, that Mrs. Austin suspected them of being the pollenizing [sic] agents. Also in pitchers of all species (possibly excepting psittacina), live spiders are very often present; sometimes web-spinning species making themselves at home there, often active jumping spiders. The literature of Nepenthes contains references to spiders supposed to be regular associates of these Oriental pitcher lants, and a study of our species might result in similar recognition among our species.

Acarids are sometimes numerous, moving about on the inner walls of several species of the Sarraceniaceae, but the occasion for their presence was not observed.

Insects robbing the leaves of their captures

A few other species occur [within the Sarracenia leaves] with less regularity. An active leopterous larva among captures of flava, when reared, resulted in an adult Chauliognathus. This species has not been observed under such circumstances again.

See also Ants and Insectivorous Plants

Birds and Pitcher Plants

At Summerville, SC, both [in] 1907 and 1915, a very large proportion of the older (over-wintered) leaves of minor were observed to have been ripped open from top to bottom (birds?), giving access to captured insects or to semicrocea larvae; similarly, [in] 1907, flava leaves showing pupa abstracted, apparently by birds which had learned the significance of that larvae-provided means of exit. 

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