64 PROTECTION OF PLAxVTS, 1921-22 



quired a bad reputation in the City of Quebec and the surrounding district. 

 Of these defoliators principal mention will be made of the Tent Caterpillars, 

 the Elm Caterpillar, and the White marked Tussock Moth. 



The Tent Caterpillars {Malocosoma americana and M. disstria). 



In 1912 countless armies of tent caterpillars completely stripped the maples 

 and other trees that were objects of pride in the parks and along the highways. 

 Two sister species belonging to the Lasiocampidse family, worked concertedl}^ — 

 the American and the Forest caterpillars. They are very similar in habits, the 

 first, however, preferring the apple, the second the forest trees, but both feeding 

 upon succulent foliage of all kinds when they occur in large numbers in the same 

 localit3\ It should be added that the Forest Caterpillar, in spite of its comonm 

 name does not build a tent. 



The life history of these two insects may be summarized as follows: they 

 winter as eggs arranged as large rings, each containing 150-300 shells, around the 

 smaller branches of the trees selected by the females for egg-laying. At the end 

 of May or about the beginning of June, the eggs hatch and the little caterpillars 

 make for the leaves in quest of food. The true tent caterpillars live in colonies 

 in a sort of house made of threads secreted by the larvae, situated at the crotch 

 of two branches, and capable of sheltering 100-250 caterpillars. 



The other species has only the power of making a silk thread wherever it 

 goes. Up to the 15th or 20th of June the trees are either partially or wholly 

 defoliated, according to the number of caterpillars that are working. At this 

 time the caterpillars are about two inches long and are fully grown. They then 

 leave the host plant and wander here and there until they find a suitable hiding 

 place. There they form a cocoon of whitish silk within which they make their 

 transformation to a pupa. Ten or fifteen days later, moths emerge from the 

 cocoons. In the first days of July mating and egg-laying occur; at that time 

 myriads of the moths can be seen flying about the lamps of our cities. The 

 reproduction of the species having been assured the mission of the adult insect 

 is ended and it dies. The eggs are the only evidence of life until the following- 

 spring. 



The Elm Caterpillar (Vanessa autiopa L.) 



The Elm Caterpillar belongs to the Nj^iiphalidse family of the Lepidoptera. 

 It is a black caterpillar marked with chestnut spots and bearing a cuirass of 

 long forked spines. We have found it quite numerous on the elms of the city 

 of Quebec during the last five years. The leaves of the elm are its favorite food 

 and it gets nourishment from them in a strange way. The green portion filled 

 with chlorphyll is very appetizing, for after the visit there remains only a skele- 

 ton of veins covering the upper epidermis which has remained intact and become 

 transparent, the whole assuming a yellow color. 



The caterpillar does not appear until the last half of July, and it requires 

 four weeks to attain full growth. It is then two inches long and it roams about 

 at random seeking a suitable place in which to transform to a chrysaHs. Unable 

 to spin a cocoon it adopts the very simple procedure of suspending itself by the 



