During mid-summer the bees and wasps are very busy building their nests and rearing their young. The Humble bees, late in June and the first of this month, send out their first broods of workers, and about the middle of the month the second lot of eggs are laid, which produce the smaller-sized females and males, while eggs laid late in the month and early in August, produce the larger-sized queens, which soon hatch. These hibernate. The habits of their peculiar parasite, Apathus, an insect which closely resembles the Humble bee, are still unknown. [Illustration: 252. White-faced Wasp.] The Leaf-cutter bee (Megachile) may be seen flying about with pieces of rose-leaf, with which she builds, for a period of twenty days, her cells, often thirty in number, using for this purpose, according to Mr. F. W. Putnam's estimate,[32] at least one thousand pieces! The bees referred to "worked so diligently that they ruined five or six rose-bushes, not leaving a single unblighted leaf uncut, and were then forced to take the leaves of a locust tree as a substitute." The Paper-making wasps, of which Vespa maculata (Fig. 252), the "White-faced wasp," is our largest species, are now completing their nests, and feeding their young with flies. The Solitary wasp (Odynerus albophaleratus) fills its earthen cells with minute caterpillars, which it paralyzes with its poisonous sting. A group of mud-cells, each stored with food for the single larva within, we once found concealed in a deserted nest of the American Tent caterpillar. Numerous species of Wood wasps (Crabronidae) are engaged in tunnelling the stems of the blackberry, the elder, and syringa, and enlarging and refitting old nail holes, and burrowing in rotten wood, storing their cells with flies, caterpillars, aphides and spiders, according to the habit of each species. Eumenes fraterna, which attaches its single, large, thin-walled cell of mud to the stems of plants, is, according to Dr. T. W. Harris, known to store it with Canker worms. Pelopaeus, the Mud-dauber, is now building its earthen cells, plastering them on old rafters and stone walls. The Saw flies (Tenthredo), etc., abound in our gardens this month. The Selandria vitis attacks the vine, while Selandria rosae, the Rose slug, injures the rose. The disgusting Pear slug-worm (S. cerasi), often live twenty to thirty on a leaf, eating the parenchyma, or softer tissues, leaving the blighted leaf. The leaves should be sprinkled with a mixture of whale-oil soap and water, in the proportion of two pounds of soap to fifteen gallons of water. [Illustration: 253. Imported Cabbage Butterfly.]