Colopha ulmicola

Colopha ulmicola

Byrsocrypta ulmicola Fitch. 
Thelaxes ulmicola Walsh. 
Pemphigus ulmicola Packard. 
Pemphigus ulmicola Smith. 
Colopha ulmicola Monell. 
Glyphina ulmicola Thomas. 
Colopha compressa (Koch) Lichtenstein and Cholodkovsky et al. 
Colopha eragrostidis Middleton.

In spite of the fact that this species is recorded by many and from many localities, very few original observations have been published since the Riley-Monell paper. From the character of most of the records of Colopha ulmicola it is quite impossible to tell whether they refer to ulmicola or colophoidea. Probably a verbatim quotation of the more significant accounts would be a convenience for the purposes of this bulletin, — that is to bring together what is known concerning the gall aphids of the elm for America. 

Fitch's characterization (1858) is reproduced entire as follows: 

"347. Elm Gall-louse, Byrsocrypta Ulmicola, new species (Homoptera. Aphidae.) 

"In June, an excrescence or follicle like a cock's comb, arising abruptly from the upper surface of the leaf, usually about an inch long and a quarter of an inch high, compressed and its sides wrinkled perpendicularly and its summit irregularly gashed and toothed, of a paler green color than the leaf and more or less red on the side exposed to the sun; opening on the under side of the leaf by a long slit-like orifice; inside wrinkled perpendicularly into deep plaits and occupied by one female and a number of her young, some of which are often strolling outside upon the under surface of the leaf, minute oval yellowish white lice 0.02 long, with blackish legs, the female more or less coated with white meal on her back, 0.07 long, oval and pale yellow with blackish legs and antennae. Though I have not yet met with winged individuals, they in all probability pertain to the genus to which I have referred this species above. The galls may frequently be noticed on elm leaves. By the middle of summer they become tenantless, dry and hard and of a blackish brown color." 

Walsh's (1862) description of the insect reads: 

"Thelaxes ulmicola Fitch. Occurs in elm-leaf galls, which are well-described by Fitch"

Riley in the Riley-Monell paper gives the following discussion of Colopha ulmicola which is reproduced entire:

 "COLOPHA* ULMICOLA (Fitch). "(Forming cock's-comb-like galls (Fig. 129 a) on the upper surface of the leaves of Ulmus americana, the galls appearing with the opening of the leaves, and turning brown and black in late summer.)

"Another very common gall, which may be called the Cock's-comb Elm Gall (ulmi-ulmicola) is also found on the White Elm, and particularly as in the case of the previous gall, on young trees. It was well described by Fitch as an excrescence or follicle like a cock's comb, arising abruptly on the tipper side of the leaves, usually one inch long and 1/4 of an inch high, compressed and its sides wrinkled perpendicularly and its summit irregularly gashed and toothed; of a paler green color than the leaf and more or less red on the side exposed to the sun; opening on the under side of the leaf by a long slit-like orifice; inside wrinkled perpendicularly into deep plates. The gall is always found between two of the branching parallel veins, and those between which it grows are generally drawn closer together than the rest. The corrugations and roughness, so characteristic of this gall, evidently result from the lesser susceptibility of the minute transverse veins to swell, compared with the more succulent tissue of the leaf. There is always a certain hoariness around the mouth of the gall below, while the base of the upper part is always contracted and compressed.

Thomas (1879) gives for this species besides a systematic discussion, the following characterization: 

"Glyphyina ulmicola. Fitch. The Aphis of the Elm-leaf Cockscomb gall.  

"This species forms the cone-shaped galls, so common on the upper side of the leaves of young white elms. These galls, which are often an inch or more in length, vary in height, from one to three-quarters of an inch; they are compressed and grooved on the sides, and perpendicular, showing tooth-like, conical projections at the top: opening by a long slit on the under side. The inside is wrinkled perpendicularly into deep plaits or folds, and occupied by one female and her progeny, some of which may often be seen strolling out on the under side of the leaf.

[Patch goes on to discuss the anatomical distinctions between aphids of these putative species at length]

[Notes:]

Colopha ulmicola is considered by some the same as Colopha compressa of Europe. Even if this be the case, I have chosen to retain the American name for this species because it seems discreet to be entirely sure of the relations of this insect in one country before getting it involved with European problems. 

So far as the literature is concerned the cockscomb gall in America has been so constantly associated with Colopha ulmicola that it was with considerable surprise that I found that the species issuing from the cockscomb gall in Maine in 1909 was not a Colopha but a Tetraneura. This cockscomb Tetraneura was, it seems, first taken by that most excellent observer Mr. Pergande years ago and in a correspondence with Mr. Monell received the name of Tetraneura colophoidea Monell mss. This species was described and figured under the name of Tetraneura ulmi (by error) by Mr. Sanborn, but the name of colophoidea never escaped manuscript except in a paper "Upon the Aphis-feeding Species of Aphelinus" by Doctor Howard, where it was merely mentioned. 

The differences between T. colophoidea and C. ulmicola except for the venation are perhaps not such as would definitely separate these species, but as the venation runs constant in certain large collections it seems expedient to consider them as distinct unless future study shall show them to be dimorphic forms of the same species. There can be no doubt that Tetraneura colophoidea is the elm gall form of graminis (on grass). Similarly there seems no longer any reason to hold Colopha eragrostidis (on grass) distinct from ulmicola of the elm.



Gall aphids of the elm