9i THE REPORT OF THE Xo. 36 



In our days, conchologists are rather numerous and with them the science 

 of mollusks has enormously advanced. However, those who are interested in 

 economic zoology, in the relations of heasts with cultivated plants particularly, 

 still have much to learn as regards their habits, the noxiousness and the destructive 

 work of our garden slugs. 



The summer of 1918 seems to have been very propitious to observers and 

 experimentalists. Slugs have increased in number in 12 months and their des- 

 tructive work has developed. Many " war gardens " in the vicinity of Quebec 

 have had to stand the attacks of these destroyers, usually unknown to average 

 people, in this capacity at least. We might say that we have very often seen 

 considerable damage ; amateur gardeners were so much the more puzzled because 

 they could not see the culprit at work. The ordinary species found in our gardens 

 are : Limax campestris, L. agresiis, L. maximus. 



The three of them seem to operate in the same manner. Everywhere they 

 have injured several kinds of vegetables, never all at a time but rather one after 

 the other. Is this a question of inclination, of caprice, of instinct or hazard? 

 All hypotheses are allowed, and each of these agents probably has some influence 

 upon the work, the choice of the beast. 



The following is the order followed by the slugs and the vegetables they 

 successively infested : 



1. Beans. — The first vegetable infested everywhere, the slug only changing its 

 food when this first plant has become inadequate. 



2. Peas. — The relationship between beans and peas no doubt explains this 

 transition and the appetite of the ravager. 



3. Turnips.— Mt^T leaving peas, slugs spend most of the summer on turnip 

 leaves, into which they cut large holes, with different contours. 



4. Cahhages and Cauliflowers. — These crucifers equally attract slugs. At 

 first, they are only seen on turnips, then upon all of them simultaneously. 



5. Pumphifis. — Towards the end of the season, when the pumpkin has as- 

 sumed a good round shape and is swelled with, juice, the slug penetrates into the 

 pulp and l)ores holes often as much as two inches deep. 



Authors have noted the preference of slugs for cucumbers. For one reason 

 or another, their presence upon this plant has nowdiere been noticed by us, 

 although, in most cases, the latter were close neighbors to turnips thoroughly 

 infested by slugs. 



The places they like best are gardens with a damp soil, naturally wet or kept 

 in that condition artificially. 



The slug does not only eat the plants at night ; the weather seems to direct 

 its line of conduct. We have seen slugs at work at night, after its coolness 

 began to be felt; this is evidently the most common habit. The darkness of the 

 night, however, is not indispensa])le to the coming out of these animals. They 

 willingly show uj) when it is raining; if the sky is cloudy and the humidity 

 of the air high, they will sometimes be seen upon the leaves. Their presence 

 can even be noticed in the daytime, when the sun is shining brightly, on parts 

 of vegetables that are well shaded and where the moisture will easily be retained, 

 as, for instance, between rows of peas that have grown high and thick. It seems 

 that the only factor essential to their activity is moisture and the absence of 

 a bright light. Moreover, this is very easy to ascertain l)y a simple experiment : 

 if vegetables are watered at the close of day, they come out almost immediately 

 and much earlier than usual. 



