Astakines are hematopoietic cytokines originally isolated from crustaceans. We identified three astakine‐like transcripts in the tarnished plant bug (Lygus lineolaris), LlAst‐1, LlAst‐2 and LlAst‐3, containing prokineticin domains. Quantitative real‐time PCR showed variation in expression patterns of astakines in different tissues and between sexes. Relative expression levels of LlAst‐1 were highest in the fat bodies of females, while LlAst‐2 expression was highest in the fat bodies of both males and females. LlAst‐3 expression was higher in male legs compared with the female legs, but lower in all other tissues. Infection with the entomopathogenic fungus Beauveria bassiana slightly elevated LlAst‐1 expression 48 h after infection in both males and females. In contrast, the expression levels of LlAst‐2 and LlAst‐3 were not significantly changed in males and females. Compared with 12:00 h, LlAst‐1 level was higher in both sexes at 18:00 h and 00:00 h (midnight). By 6:00 h, the LlAst‐1 level in females was significantly reduced while that in males remained high. LlAst‐2 and ‐3 had highest relative expression levels in females at midnight but were significantly lower than in males at midnight and in both sexes at 18:00 h and 6:00 h. This is the first report of expression of astakine‐like cytokines from insects.