76 THE REPORT OF THE No. 1» 



During the past two summers the foliage of birch trees of all kinds, was badly attacked by 

 the larvje of Bucc/iilatrix Cmiadensisella, Cham. These small caterpillars occurred in vast num- 

 bers throughout Ontario, but were not noticed by the public until late in August when the 

 tiees assumed a seared appearance, and the leaves were dropping prematurely. These larvje 

 are popularly known as the Birch Skeletonizer, from the way they eat away the cellular tissue 

 of che foliage, leaving only the fibrous skeleton, and are of considerable interest from the 

 peculiar habit they have, which is quite unusual, of spinning on the leaves, before full grown, 

 flat circular shelters, called pseudo-cocoons, whenever they are ready to moult. These little 

 shelters, which of course are only large enough to contain the one larva, are only used by the 

 caterpillars about a day or so before the process of casting their skin. 



An interesting example of a caterpillar illustrating protective mimicry was observed last 

 season by Dr. Fletcher and the writer. In May, 1901, larvse of one of the noctuid moths, 

 Hom0hadena badistriga, Grt. , were found in some numbers on the yellow-flowered honey- 

 suckle, Lonicera hirsutcif Eaton. Caterpillars in all stages were found, but strange to say no 

 trace of eggs could be seen. Very small larvse were collected about a quarter of an inch long, 

 which must have been out of the egg only a day or so. Doubtless, as is often the case, the 

 young caterpillar made its first meal of the shell from which it had emerged. It is probable 

 that some eggs were still on the plant, but although searched for diligently, none could be 

 discovered. When young the caterpillars feed on the foliage of the new shoots of the plant 

 and generally hide inside the two clasping leaves which surround the cluster of flower buds at 

 the tip. When mature they crawl down to the shady side of the old wood of the plant, upon 

 which they rest when not feeding. At this time che general colour of the caterpillar is remark- 

 ably like that of the stem, or twig, upon which it is resting, and owing to this striking resem- 

 blance, it is thus protected from numerous enemies. 



Many other larvse owing to their colour being similar to that of the plant upon which they 

 feed are likewise hidden from view, and unless searched for carefully, even when they are 

 known to be present, are diflicult to find. Plusia cereoides, Grt., which feeds on Solidago Can- 

 adensis, L., is another example of a corresponding similarity in coloration of the caterpillar 

 to the green colour of the leaves and stem, protecting the species from natural enemies, such 

 as birds, parasites, etc. 



The larva of iVertce feidentoto, Walk. , feeds on the foliage of elm ; it is a rather curious 

 caterpillar with sharp protuberances down the dorsum. This species feeds on the edge of a 

 leaf, and owing to its colour being the same as that of the foliage, and its peculiar elevations 

 on the dorsum corresponding with the outline of the leaf, it is thus protected considerably from 

 being observed. A similar example of protective resemblance is found in the caterpillar of 

 Telea polyphemus. Cram., which when feeding on the edge of an elm leaf from which it has 

 eaten out a portion, is even better protected than the above by reason of its indented dorsal 

 outline and the bright lateral stripes, which simulate the ribs of the leaf. 



An interesting habit which certain of the Coliad larvee have, is that of resting exactly in 



the same place, after feeding, along the mid rib of a leaf. When wandering off to feed they 



spin a path of fine silk as they walk. After they have eaten their meal they are thus able to 



^^^^^ return by following this silken road to the exact 



^H^nj^^^^^^ spot from which they first started. Papilio 



~ — ^~-^l|^^WwP™iPHPl^ turnus, Linn., also has the habit of spinning a 



'''''^^'^^^.,.^- ,'fffjMf^/^^^^^^e^^ platform of silk across the upper side of a leaf 



"""'"'^^^^^^^^^^^^^^^^^^ upon which it rests when not feeding. (Fig. 53). 

 „• -o r . D I- . Doubtless every collector of insects, or 



Fig. o3. Larva of Papilio turnus. ■' . ' 



student of natural history, has noticed the habit 

 which many caterpillars h<*ve of drawing two or more leaves together by means of threads of 



