402 



Observations on the various Insects 



as well as by shaking the branches over sieves, which were 

 emptied into pails of water. The beetles are, however, so timid 

 and wary, that they are most successfully collected without lan- 

 terns; and if lights be used^ the infested pJants must be very 

 cautiously approached, otherwise the weevils will fall down and 

 escape. Possibly by dusting with soot, lime^ or wood-ashes, and 

 watering with gas- water, the ground might be made disagree- 

 able to them ; and rows of young peas might be, in a measure, 

 protected by boards, 3 or 4 inches high, set on each side, and 

 sloping outward. As soon as the peas make their appearance 

 above ground the boards should be tarred on both sides, so that 

 the beetles could not surmount them, and many of those enclosed 

 between the boards would, no doubt, be caught by the adhesive 

 tar. 



We are, however, indebted to a genus of sand-wasps for reduc- 

 ing the numbers of these pests, which could not otherwise be 

 kept in check. Their services are unceasing and invaluable — and 

 it IS a law of nature that as the insect-plague spreads, the j)ara- 

 sites that prey upon them increase in an equal or greater degree, 

 until the mischief is subdued. Some of these sand-wasps often 

 appear in vast numbers, especially in gravelly ground and sandy 

 banks, where they form burrows to lay their eggs and rear their 

 young, and for this purpose some species fly abroad in search of 

 a group of wild bees called Andrena,'^ whilst others are engaged 

 in collecting the weevds, which they bury in their subterranean 

 nests, to feed their young maggots as soon as the eggs hatch. In 

 the gravel-walk of a garden at Boulogne-sur-mer, in August, 

 there were innumerable holes made by these sand- wasps, and 

 the females were busily occupied in carrying home a species of 

 weevil closely allied to the Otiorhynchus picipes, and described 

 under the name of O. scabrosus. On digging about a foot deep I 

 found several of the beetles which had been thus buried, the 

 contents of whose bodies had been completely emptied out, and 

 nothing was left but the horny shells. t O, sulcatus is another 

 species ; they have been detected carrying alive between their 

 legs: and a different genus of weevils, called Strophe somus,t has 

 been recorded as falling a prey to them. 



These sand-wasps are of the Order Hymenoptera, Family 

 Cercerid^, and Genus Cerceris. The species which buries the 

 weevils is named by Linn8eus 



2. C. arenaria, but it is the C. Iseta of Fabricius. The female 

 (fig. 11) is black, thickly punctured and pubescent; the head is large, 



* Curtis's Brit. Ent., fol. and pi. 129. t Curtis's Brit. Ent., fol. GOO. 

 % Curtis's Guide, Genus 374b ; and Shuckard's Fossorial Hymenoptera, 

 p. 235. 



