アシナガバチ（脚長蜂、英: Paper wasp）は、スズメバチ科アシナガバチ亜科に属する細身で小型のハチです。性格はおとなしく、巣を刺激しなければ刺してくることはほとんどありません。むしろ、アシナガバチは蛾や蝶の幼虫を捕食するため、害虫駆除に役立つ益虫です。特に初夏には、アシナガバチの巣があることでモンシロチョウの幼虫が増えず、キャベツなどの作物を殺虫剤やネットを使わずに栽培・収穫することが可能です。無農薬栽培に適しており、多少の食痕が残る程度で済みます。

巣の構造はスズメバチの巣とは異なり、光沢のある外皮を持たず、ハスの花托や果托に似た形状をしています。アシナガバチの巣は、枯れ木ではなく樹皮の靭皮繊維を使用し、唾液由来のタンパク質と混ぜ合わせた強靭な巣材で作られます。これにより、巣は一般的なスズメバチの巣よりも丈夫で、スズメバチの巣が洋紙にたとえられるのに対し、アシナガバチの巣は和紙に例えられることがあります。

巣の直径はおよそ10 cmほどで、女王蜂は比較的低い乾燥した場所に巣を作ります。3部屋ほど作るとすぐに卵を産み、約20日で幼虫が成虫になります。巣作りの時期は4〜5月頃で、巣は蓮の実に似た形で作られ、100部屋を超えることもあります。中央の幼虫が巣立つと再び卵が産み付けられますが、ミツバチのように蜜をためることはありません。11月頃には働き蜂が全て死に、女王蜂だけが冬眠します。巣は一度しか使われず、空になった巣は再利用されません。

アシナガバチは尾部の毒針で刺すことができますが、性質はスズメバチに比べて穏やかで、巣を強く刺激したり蜂を素手で触らない限り、刺されることは少ないです。刺傷の多くは、子供が巣を刺激したり、洗濯物に紛れ込んだ蜂に気づかずに起こります。アシナガバチの毒はスズメバチに比べて弱く、毒による死亡は稀ですが、アナフィラキシーショックによる死亡のリスクもあります。過去に刺されたことがある人は注意が必要です。しかし、実際に刺されて死亡する人は数千人に一人程度です。

Paper wasp nest
The Paper wasp (scientific name: Polistes, belonging to the subfamily Polistinae in the family Vespidae) is a slender and small species of wasp. They are generally docile and rarely sting unless their nest is disturbed. In fact, paper wasps are beneficial insects as they prey on larvae of moths and butterflies, helping in pest control. Particularly in early summer, their presence can reduce the population of cabbage white caterpillars, making it possible to grow and harvest crops like cabbage without the need for pesticides or nets. This makes them well-suited for organic farming, as they leave only minimal feeding marks on crops.

The structure of their nests is different from that of hornets. Unlike hornet nests, which have a glossy outer layer, paper wasp nests resemble the seed pods or fruit of a lotus plant. Their nests are made from durable material, created by mixing fibers from tree bark with protein from their saliva. This makes their nests stronger than typical hornet nests, which are often compared to western-style paper, while paper wasp nests are sometimes likened to traditional Japanese washi paper.

The diameter of a paper wasp nest is approximately 10 cm. The queen builds her nest in relatively low, dry locations, and after creating about three cells, she begins to lay eggs. It takes around 20 days for larvae to mature into adult wasps. Nest-building typically occurs between April and May, with nests taking on a lotus seed-like shape, and some nests can have over 100 cells. Once the central larvae leave the nest, the queen lays more eggs, though paper wasps do not store honey like bees. By November, all worker wasps die, and only the queen hibernates. The nest is used only once and is not reused once it becomes vacant.

Though paper wasps can sting with a venomous stinger at the end of their abdomen, they are less aggressive than hornets. You are unlikely to be stung unless you disturb their nest or handle them bare-handed. Most stings occur when children unknowingly provoke a nest or when a wasp gets caught in laundry. The venom of paper wasps is weaker compared to hornets, and fatalities from their sting are rare, though there is a risk of anaphylactic shock, especially for those who have been stung before. However, the chance of dying from a paper wasp sting is about one in several thousand.

#アシナガバチ #Paperwasp. #蜂 #Polistinae